diff --git a/src/bauhaus/bauhaus.c b/src/bauhaus/bauhaus.c
index 26b771884b78..c69716b95479 100644
--- a/src/bauhaus/bauhaus.c
+++ b/src/bauhaus/bauhaus.c
@@ -673,7 +673,6 @@ static gboolean _popup_button_release(GtkWidget *widget,
 
   return TRUE;
 }
-
 static gboolean _popup_button_press(GtkWidget *widget,
                                     GdkEventButton *event,
                                     gpointer user_data)
@@ -715,10 +714,10 @@ static gboolean _popup_button_press(GtkWidget *widget,
   return TRUE;
 }
 
-static void _window_show(GtkWidget *w, gpointer user_data)
+static void _window_show(GtkWidget *w, GtkWidget *area)
 {
   // make sure combo popup handles button release
-  gtk_grab_add(GTK_WIDGET(user_data));
+  gtk_grab_add(area);
 }
 
 static void _widget_leave(GtkEventControllerMotion *controller,
@@ -892,20 +891,17 @@ void dt_bauhaus_init()
                         | GDK_KEY_PRESS_MASK | GDK_LEAVE_NOTIFY_MASK
                         | darktable.gui->scroll_mask);
 
-  GObject *window = G_OBJECT(pop->window);
-  GObject *area = G_OBJECT(pop->area);
-
   gtk_widget_realize(pop->window);
   g_signal_connect(gtk_widget_get_window(pop->window),
                    "moved-to-rect", G_CALLBACK(_window_moved_to_rect), NULL);
-  g_signal_connect(window, "show", G_CALLBACK(_window_show), area);
-  g_signal_connect(window, "motion-notify-event", G_CALLBACK(_window_motion_notify), NULL);
-  g_signal_connect(area, "draw", G_CALLBACK(_popup_draw), NULL);
-  g_signal_connect(area, "leave-notify-event", G_CALLBACK(_popup_leave_notify), NULL);
-  g_signal_connect(area, "button-press-event", G_CALLBACK(_popup_button_press), NULL);
-  g_signal_connect(area, "button-release-event", G_CALLBACK (_popup_button_release), NULL);
-  g_signal_connect(area, "key-press-event", G_CALLBACK(_popup_key_press), NULL);
-  g_signal_connect(area, "scroll-event", G_CALLBACK(_popup_scroll), NULL);
+  g_signal_connect(pop->window, "show", G_CALLBACK(_window_show), pop->area);
+  g_signal_connect(pop->window, "motion-notify-event", G_CALLBACK(_window_motion_notify), NULL);
+  g_signal_connect(pop->area, "draw", G_CALLBACK(_popup_draw), NULL);
+  g_signal_connect(pop->area, "leave-notify-event", G_CALLBACK(_popup_leave_notify), NULL);
+  g_signal_connect(pop->area, "button-press-event", G_CALLBACK(_popup_button_press), NULL);
+  g_signal_connect(pop->area, "button-release-event", G_CALLBACK (_popup_button_release), NULL);
+  g_signal_connect(pop->area, "key-press-event", G_CALLBACK(_popup_key_press), NULL);
+  g_signal_connect(pop->area, "scroll-event", G_CALLBACK(_popup_scroll), NULL);
 
   dt_action_define(&darktable.control->actions_focus, NULL, N_("sliders"),
                    NULL, &_action_def_focus_slider);
diff --git a/src/bauhaus/bauhaus.h b/src/bauhaus/bauhaus.h
index f941b9fb9c03..517f0595365f 100644
--- a/src/bauhaus/bauhaus.h
+++ b/src/bauhaus/bauhaus.h
@@ -212,7 +212,7 @@ static inline void dt_bauhaus_widget_set_quad(GtkWidget *widget,
 {
   dt_bauhaus_widget_set_quad_paint(widget, paint, 0, NULL);
   dt_bauhaus_widget_set_quad_toggle(widget, toggle);
-  g_signal_connect(G_OBJECT(widget), "quad-pressed", G_CALLBACK(callback), self);
+  g_signal_connect(widget, "quad-pressed", G_CALLBACK(callback), self);
   if(tooltip) dt_bauhaus_widget_set_quad_tooltip(widget, tooltip);
 }
 // get the tooltip for widget or quad button:
diff --git a/src/common/camera_control.c b/src/common/camera_control.c
index f89ccb46e7b1..66262710a899 100644
--- a/src/common/camera_control.c
+++ b/src/common/camera_control.c
@@ -1677,7 +1677,7 @@ static void _camera_build_property_menu(CameraWidget *widget,
           /* construct menu item for property */
           gp_widget_get_name(child, &sk);
           GtkMenuItem *item = GTK_MENU_ITEM(gtk_menu_item_new_with_label(sk));
-          g_signal_connect(G_OBJECT(item), "activate", item_activate, user_data);
+          g_signal_connect(item, "activate", G_CALLBACK((void(*)(GtkMenuItem*,gpointer))item_activate), user_data);
           /* add submenu item to menu */
           gtk_menu_shell_append(GTK_MENU_SHELL(menu), GTK_WIDGET(item));
         }
diff --git a/src/control/crawler.c b/src/control/crawler.c
index f5bec053640a..8cb07b33243f 100644
--- a/src/control/crawler.c
+++ b/src/control/crawler.c
@@ -348,25 +348,24 @@ static void _delete_selected_rows(dt_control_crawler_gui_t *gui)
 
 
 static void _select_all_callback(GtkButton *button,
-                                 gpointer user_data)
+                                 dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
   gtk_tree_selection_select_all(selection);
 }
 
 
-static void _select_none_callback(GtkButton *button, gpointer user_data)
+static void _select_none_callback(GtkButton *button,
+                                 dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
   gtk_tree_selection_unselect_all(selection);
 }
 
 
-static void _select_invert_callback(GtkButton *button, gpointer user_data)
+static void _select_invert_callback(GtkButton *button,
+                                    dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
 
   GtkTreeIter iter;
@@ -634,9 +633,8 @@ static void sync_oldest_to_newest(GtkTreeModel *model,
 }
 
 // overwrite database with xmp
-static void _reload_button_clicked(GtkButton *button, gpointer user_data)
+static void _reload_button_clicked(GtkButton *button, dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
   gui->rows_to_remove = NULL;
   gtk_spinner_start(GTK_SPINNER(gui->spinner));
@@ -646,9 +644,8 @@ static void _reload_button_clicked(GtkButton *button, gpointer user_data)
 }
 
 // overwrite xmp with database
-void _overwrite_button_clicked(GtkButton *button, gpointer user_data)
+void _overwrite_button_clicked(GtkButton *button, dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
   gui->rows_to_remove = NULL;
   gtk_spinner_start(GTK_SPINNER(gui->spinner));
@@ -658,9 +655,8 @@ void _overwrite_button_clicked(GtkButton *button, gpointer user_data)
 }
 
 // overwrite the oldest with the newest
-static void _newest_button_clicked(GtkButton *button, gpointer user_data)
+static void _newest_button_clicked(GtkButton *button, dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
   gui->rows_to_remove = NULL;
   gtk_spinner_start(GTK_SPINNER(gui->spinner));
@@ -670,9 +666,8 @@ static void _newest_button_clicked(GtkButton *button, gpointer user_data)
 }
 
 // overwrite the newest with the oldest
-static void _oldest_button_clicked(GtkButton *button, gpointer user_data)
+static void _oldest_button_clicked(GtkButton *button, dt_control_crawler_gui_t *gui)
 {
-  dt_control_crawler_gui_t *gui = (dt_control_crawler_gui_t *)user_data;
   GtkTreeSelection *selection = gtk_tree_view_get_selection(gui->tree);
   gui->rows_to_remove = NULL;
   gtk_spinner_start(GTK_SPINNER(gui->spinner));
@@ -810,19 +805,19 @@ void dt_control_crawler_show_image_list(GList *images)
   GtkWidget *select_all = gtk_button_new_with_label(_("select all"));
   GtkWidget *select_none = gtk_button_new_with_label(_("select none"));
   GtkWidget *select_invert = gtk_button_new_with_label(_("invert selection"));
-  g_signal_connect(select_all, "clicked", G_CALLBACK(_select_all_callback), gui);
-  g_signal_connect(select_none, "clicked", G_CALLBACK(_select_none_callback), gui);
-  g_signal_connect(select_invert, "clicked", G_CALLBACK(_select_invert_callback), gui);
+  g_signal_connect(GTK_BUTTON(select_all), "clicked", G_CALLBACK(_select_all_callback), gui);
+  g_signal_connect(GTK_BUTTON(select_none), "clicked", G_CALLBACK(_select_none_callback), gui);
+  g_signal_connect(GTK_BUTTON(select_invert), "clicked", G_CALLBACK(_select_invert_callback), gui);
 
   GtkWidget *label = gtk_label_new_with_mnemonic(_("on the selection:"));
   GtkWidget *reload_button = gtk_button_new_with_label(_("keep the XMP edit"));
   GtkWidget *overwrite_button = gtk_button_new_with_label(_("keep the database edit"));
   GtkWidget *newest_button = gtk_button_new_with_label(_("keep the newest edit"));
   GtkWidget *oldest_button = gtk_button_new_with_label(_("keep the oldest edit"));
-  g_signal_connect(reload_button, "clicked", G_CALLBACK(_reload_button_clicked), gui);
-  g_signal_connect(overwrite_button, "clicked", G_CALLBACK(_overwrite_button_clicked), gui);
-  g_signal_connect(newest_button, "clicked", G_CALLBACK(_newest_button_clicked), gui);
-  g_signal_connect(oldest_button, "clicked", G_CALLBACK(_oldest_button_clicked), gui);
+  g_signal_connect(GTK_BUTTON(reload_button), "clicked", G_CALLBACK(_reload_button_clicked), gui);
+  g_signal_connect(GTK_BUTTON(overwrite_button), "clicked", G_CALLBACK(_overwrite_button_clicked), gui);
+  g_signal_connect(GTK_BUTTON(newest_button), "clicked", G_CALLBACK(_newest_button_clicked), gui);
+  g_signal_connect(GTK_BUTTON(oldest_button), "clicked", G_CALLBACK(_oldest_button_clicked), gui);
 
   /* Feedback spinner in case synch happens over network and stales */
   gui->spinner = gtk_spinner_new();
diff --git a/src/control/signal.c b/src/control/signal.c
index b2595d4c0736..e6f91b041a25 100644
--- a/src/control/signal.c
+++ b/src/control/signal.c
@@ -93,6 +93,7 @@ static void _image_geotag_destroy_callback(gpointer instance, gpointer imgs, con
     imgs = NULL;
   }
 }
+#define G_CALLBACK(f) ((GCallback) (f))
 
 static dt_signal_description _signal_description[DT_SIGNAL_COUNT] = {
   /* Global signals */
@@ -241,7 +242,7 @@ dt_control_signal_t *dt_control_signal_init()
         _signal_description[k].n_params, _signal_description[k].param_types);
     if(_signal_description[k].destructor)
     {
-      g_signal_connect_after(G_OBJECT(ctlsig->sink), _signal_description[k].name,
+      g_signal_connect_after(ctlsig->sink, _signal_description[k].name,
                              _signal_description[k].destructor, NULL);
     }
   }
@@ -394,7 +395,7 @@ void dt_control_signal_connect(const dt_control_signal_t *ctlsig, dt_signal_t si
 {
   _print_trace(signal, DT_DEBUG_SIGNAL_ACT_CONNECT, "connect");
 
-  g_signal_connect(G_OBJECT(ctlsig->sink), _signal_description[signal].name, G_CALLBACK(cb), user_data);
+  g_signal_connect_data(ctlsig->sink, _signal_description[signal].name, G_CALLBACK(cb), user_data, NULL, 0);
 }
 
 void dt_control_signal_disconnect(const struct dt_control_signal_t *ctlsig, GCallback cb, gpointer user_data)
diff --git a/src/develop/blend.h b/src/develop/blend.h
index 4579f20d822a..65180f5fde5d 100644
--- a/src/develop/blend.h
+++ b/src/develop/blend.h
@@ -260,7 +260,7 @@ typedef struct dt_iop_gui_blendif_channel_t
   dt_develop_blendif_channels_t param_channels[2];
   dt_dev_pixelpipe_display_mask_t display_channel;
   void (*scale_print)(float value, float boost_factor, char *string, int n);
-  int (*altdisplay)(GtkWidget *, dt_iop_module_t *, int);
+  int (*altdisplay)(GtkDarktableGradientSlider *, dt_iop_module_t *, int);
   char *name;
 } dt_iop_gui_blendif_channel_t;
 
diff --git a/src/develop/blend_gui.c b/src/develop/blend_gui.c
index 6394bd0fc427..fcc7c1e2af23 100644
--- a/src/develop/blend_gui.c
+++ b/src/develop/blend_gui.c
@@ -999,14 +999,13 @@ static float _magnifier_scale_callback(GtkWidget *self,
   return outval;
 }
 
-static int _blendop_blendif_disp_alternative_worker(GtkWidget *widget,
+static int _blendop_blendif_disp_alternative_worker(GtkDarktableGradientSlider *slider,
                                                     dt_iop_module_t *module,
                                                     const int mode,
                                                     float (*scale_callback)(GtkWidget*, float, int),
                                                     const char *label)
 {
   dt_iop_gui_blend_data_t *data = module->blend_data;
-  GtkDarktableGradientSlider *slider = (GtkDarktableGradientSlider *)widget;
 
   const int in_out = (slider == data->filter[1].slider) ? 1 : 0;
 
@@ -1024,7 +1023,7 @@ static int _blendop_blendif_disp_alternative_worker(GtkWidget *widget,
 }
 
 
-static int _blendop_blendif_disp_alternative_mag(GtkWidget *widget,
+static int _blendop_blendif_disp_alternative_mag(GtkDarktableGradientSlider *widget,
                                                  dt_iop_module_t *module,
                                                  const int mode)
 {
@@ -1032,7 +1031,7 @@ static int _blendop_blendif_disp_alternative_mag(GtkWidget *widget,
     (widget, module, mode, _magnifier_scale_callback, _(" (zoom)"));
 }
 
-static int _blendop_blendif_disp_alternative_log(GtkWidget *widget,
+static int _blendop_blendif_disp_alternative_log(GtkDarktableGradientSlider *widget,
                                                  dt_iop_module_t *module,
                                                  const int mode)
 {
@@ -1040,7 +1039,7 @@ static int _blendop_blendif_disp_alternative_log(GtkWidget *widget,
     (widget, module, mode, _log10_scale_callback, _(" (log)"));
 }
 
-static void _blendop_blendif_disp_alternative_reset(GtkWidget *widget,
+static void _blendop_blendif_disp_alternative_reset(GtkDarktableGradientSlider *widget,
                                                     dt_iop_module_t *module)
 {
   (void) _blendop_blendif_disp_alternative_worker(widget, module, 0, NULL, "");
@@ -1226,11 +1225,11 @@ static void _blendop_blendif_update_tab(dt_iop_module_t *module,
     if(channel->altdisplay)
     {
       data->altmode[tab][in_out] =
-        channel->altdisplay(GTK_WIDGET(sl->slider), module, data->altmode[tab][in_out]);
+        channel->altdisplay(sl->slider, module, data->altmode[tab][in_out]);
     }
     else
     {
-      _blendop_blendif_disp_alternative_reset(GTK_WIDGET(sl->slider), module);
+      _blendop_blendif_disp_alternative_reset(sl->slider, module);
     }
   }
 
@@ -1963,7 +1962,7 @@ static gboolean _blendif_change_blend_colorspace(dt_iop_module_t *module,
   return FALSE;
 }
 
-static void _blendif_select_colorspace(GtkMenuItem *menuitem,
+static void _blendif_select_colorspace(GtkWidget *menuitem,
                                        dt_iop_module_t *module)
 {
   const dt_develop_blend_colorspace_t cst =
@@ -1974,7 +1973,7 @@ static void _blendif_select_colorspace(GtkMenuItem *menuitem,
   }
 }
 
-static void _blendif_show_output_channels(GtkMenuItem *menuitem,
+static void _blendif_show_output_channels(GtkWidget *menuitem,
                                           dt_iop_module_t *module)
 {
   dt_iop_gui_blend_data_t *bd = module->blend_data;
@@ -1986,7 +1985,7 @@ static void _blendif_show_output_channels(GtkMenuItem *menuitem,
   }
 }
 
-static void _blendif_hide_output_channels(GtkMenuItem *menuitem,
+static void _blendif_hide_output_channels(GtkWidget *menuitem,
                                           dt_iop_module_t *module)
 {
   dt_iop_gui_blend_data_t *bd = module->blend_data;
@@ -2006,20 +2005,20 @@ static void _blendif_hide_output_channels(GtkMenuItem *menuitem,
   }
 }
 
-static void _blendif_options_callback(GtkButton *button,
-                                      GdkEventButton *event,
-                                      dt_iop_module_t *module)
+static gboolean _blendif_options_callback(GtkButton *button,
+                                          GdkEventButton *event,
+                                          dt_iop_module_t *module)
 {
   if(event->button != 1
      && event->button != 2)
-    return;
+    return FALSE;
 
   const dt_iop_gui_blend_data_t *bd = module->blend_data;
 
   if(!bd
      || !bd->blendif_support
      || !bd->blendif_inited)
-    return;
+    return FALSE;
 
   GtkWidget *mi;
   GtkMenu *menu = GTK_MENU(gtk_menu_new());
@@ -2038,7 +2037,7 @@ static void _blendif_options_callback(GtkButton *button,
     mi = gtk_menu_item_new_with_label(_("reset to default blend colorspace"));
     g_object_set_data_full(G_OBJECT(mi), "dt-blend-cst",
                            GINT_TO_POINTER(DEVELOP_BLEND_CS_NONE), NULL);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(_blendif_select_colorspace), module);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
@@ -2056,7 +2055,7 @@ static void _blendif_options_callback(GtkButton *button,
       }
       g_object_set_data_full(G_OBJECT(mi), "dt-blend-cst",
                              GINT_TO_POINTER(DEVELOP_BLEND_CS_LAB), NULL);
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(_blendif_select_colorspace), module);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
     }
@@ -2070,7 +2069,7 @@ static void _blendif_options_callback(GtkButton *button,
     }
     g_object_set_data_full(G_OBJECT(mi), "dt-blend-cst",
                            GINT_TO_POINTER(DEVELOP_BLEND_CS_RGB_DISPLAY), NULL);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(_blendif_select_colorspace), module);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
@@ -2083,7 +2082,7 @@ static void _blendif_options_callback(GtkButton *button,
     }
     g_object_set_data_full(G_OBJECT(mi), "dt-blend-cst",
                            GINT_TO_POINTER(DEVELOP_BLEND_CS_RGB_SCENE), NULL);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(_blendif_select_colorspace), module);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
@@ -2092,14 +2091,14 @@ static void _blendif_options_callback(GtkButton *button,
     if(bd->output_channels_shown)
     {
       mi = gtk_menu_item_new_with_label(_("reset and hide output channels"));
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(_blendif_hide_output_channels), module);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
     }
     else
     {
       mi = gtk_menu_item_new_with_label(_("show output channels"));
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(_blendif_show_output_channels), module);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
     }
@@ -2109,10 +2108,12 @@ static void _blendif_options_callback(GtkButton *button,
                     GTK_WIDGET(button), GDK_GRAVITY_SOUTH_EAST, GDK_GRAVITY_NORTH_EAST);
 
   dtgtk_button_set_active(DTGTK_BUTTON(button), FALSE);
+
+  return TRUE;
 }
 
 // activate channel/mask view
-static void _blendop_blendif_channel_mask_view(GtkWidget *widget,
+static void _blendop_blendif_channel_mask_view(GtkDarktableGradientSlider *widget,
                                                dt_iop_module_t *module,
                                                const dt_dev_pixelpipe_display_mask_t mode)
 {
@@ -2126,7 +2127,7 @@ static void _blendop_blendif_channel_mask_view(GtkWidget *widget,
   {
     dt_dev_pixelpipe_display_mask_t channel = data->channel[data->tab].display_channel;
 
-    if(widget == GTK_WIDGET(data->filter[1].slider))
+    if(widget == data->filter[1].slider)
       channel |= DT_DEV_PIXELPIPE_DISPLAY_OUTPUT;
 
     new_request_mask_display &= ~DT_DEV_PIXELPIPE_DISPLAY_ANY;
@@ -2143,7 +2144,7 @@ static void _blendop_blendif_channel_mask_view(GtkWidget *widget,
 
 // toggle channel/mask view
 static void _blendop_blendif_channel_mask_view_toggle
-  (GtkWidget *widget,
+  (GtkDarktableGradientSlider *widget,
    dt_iop_module_t *module,
    const dt_dev_pixelpipe_display_mask_t mode)
 {
@@ -2172,7 +2173,7 @@ static void _blendop_blendif_channel_mask_view_toggle
   {
     dt_dev_pixelpipe_display_mask_t channel = data->channel[data->tab].display_channel;
 
-    if(widget == GTK_WIDGET(data->filter[1].slider))
+    if(widget == data->filter[1].slider)
       channel |= DT_DEV_PIXELPIPE_DISPLAY_OUTPUT;
 
     new_request_mask_display &= ~DT_DEV_PIXELPIPE_DISPLAY_ANY;
@@ -2190,7 +2191,7 @@ static void _blendop_blendif_channel_mask_view_toggle
 // magic mode: if mouse cursor enters a gradient slider with shift
 // and/or control pressed we enter channel display and/or mask display
 // mode
-static gboolean _blendop_blendif_enter(GtkWidget *widget,
+static gboolean _blendop_blendif_enter(GtkDarktableGradientSlider *widget,
                                        GdkEventCrossing *event,
                                        dt_iop_module_t *module)
 {
@@ -2232,7 +2233,7 @@ static gboolean _blendop_blendif_enter(GtkWidget *widget,
 
   _blendop_blendif_channel_mask_view(widget, module, mode);
 
-  gtk_widget_grab_focus(widget);
+  gtk_widget_grab_focus(GTK_WIDGET(widget));
   return FALSE;
 }
 
@@ -2263,7 +2264,7 @@ static gboolean _blendop_blendif_leave_delayed(gpointer data)
 }
 
 // de-activate magic mode when leaving the gradient slider
-static gboolean _blendop_blendif_leave(GtkWidget *widget,
+static gboolean _blendop_blendif_leave(GtkDarktableGradientSlider *widget,
                                        GdkEventCrossing *event,
                                        dt_iop_module_t *module)
 {
@@ -2286,7 +2287,7 @@ static gboolean _blendop_blendif_leave(GtkWidget *widget,
 }
 
 
-static gboolean _blendop_blendif_key_press(GtkWidget *widget,
+static gboolean _blendop_blendif_key_press(GtkDarktableGradientSlider *widget,
                                            GdkEventKey *event,
                                            dt_iop_module_t *module)
 {
@@ -2296,7 +2297,7 @@ static gboolean _blendop_blendif_key_press(GtkWidget *widget,
   gboolean handled = FALSE;
 
   const int tab = data->tab;
-  const int in_out = (widget == GTK_WIDGET(data->filter[1].slider)) ? 1 : 0;
+  const int in_out = (widget == data->filter[1].slider) ? 1 : 0;
 
   switch(event->keyval)
   {
@@ -2650,17 +2651,17 @@ void dt_iop_gui_init_blendif(GtkWidget *blendw, dt_iop_module_t *module)
            "press 'm' to toggle mask view."));
       gtk_widget_set_tooltip_text(GTK_WIDGET(sl->head), _(slider_tooltip[in_out]));
 
-      g_signal_connect(G_OBJECT(sl->slider), "value-changed",
+      g_signal_connect(sl->slider, "value-changed",
                        G_CALLBACK(_blendop_blendif_sliders_callback), bd);
-      g_signal_connect(G_OBJECT(sl->slider), "value-reset",
+      g_signal_connect(sl->slider, "value-reset",
                        G_CALLBACK(_blendop_blendif_sliders_reset_callback), bd);
-      g_signal_connect(G_OBJECT(sl->slider), "leave-notify-event",
+      g_signal_connect(sl->slider, "leave-notify-event",
                        G_CALLBACK(_blendop_blendif_leave), module);
-      g_signal_connect(G_OBJECT(sl->slider), "enter-notify-event",
+      g_signal_connect(sl->slider, "enter-notify-event",
                        G_CALLBACK(_blendop_blendif_enter), module);
-      g_signal_connect(G_OBJECT(sl->slider), "key-press-event",
+      g_signal_connect(sl->slider, "key-press-event",
                        G_CALLBACK(_blendop_blendif_key_press), module);
-      g_signal_connect(G_OBJECT(sl->polarity), "toggled",
+      g_signal_connect(GTK_TOGGLE_BUTTON(sl->polarity), "toggled",
                        G_CALLBACK(_blendop_blendif_polarity_callback), bd);
 
       sl->box = GTK_BOX(dt_gui_vbox(label_box, dt_gui_hbox(dt_gui_expand(sl->slider), sl->polarity)));
@@ -2676,13 +2677,13 @@ void dt_iop_gui_init_blendif(GtkWidget *blendw, dt_iop_module_t *module)
                                 _("adjust the boost factor of the channel mask"));
     gtk_widget_set_sensitive(bd->channel_boost_factor_slider, FALSE);
 
-    g_signal_connect(G_OBJECT(bd->channel_boost_factor_slider), "value-changed",
+    g_signal_connect(bd->channel_boost_factor_slider, "value-changed",
                      G_CALLBACK(_blendop_blendif_boost_factor_callback), bd);
-    g_signal_connect(G_OBJECT(bd->channel_tabs), "switch_page",
+    g_signal_connect(bd->channel_tabs, "switch-page",
                      G_CALLBACK(_blendop_blendif_tab_switch), bd);
-    g_signal_connect(G_OBJECT(bd->colorpicker), "toggled",
+    g_signal_connect(bd->colorpicker, "toggled",
                      G_CALLBACK(_update_gradient_slider_pickers), module);
-    g_signal_connect(G_OBJECT(bd->colorpicker_set_values), "toggled",
+    g_signal_connect(bd->colorpicker_set_values, "toggled",
                      G_CALLBACK(_update_gradient_slider_pickers), module);
 
     dt_gui_box_add(bd->blendif_box, section, header,
@@ -2765,7 +2766,7 @@ void dt_iop_gui_init_masks(GtkWidget *blendw, dt_iop_module_t *module)
     dt_bauhaus_widget_set_label(bd->masks_combo, N_("blend"), N_("drawn mask"));
 
     dt_bauhaus_combobox_add(bd->masks_combo, _("no mask used"));
-    g_signal_connect(G_OBJECT(bd->masks_combo), "value-changed",
+    g_signal_connect(bd->masks_combo, "value-changed",
                      G_CALLBACK(dt_masks_iop_value_changed_callback), module);
     dt_bauhaus_combobox_add_populate_fct(bd->masks_combo, dt_masks_iop_combo_populate);
 
@@ -2978,7 +2979,7 @@ void dt_iop_gui_init_raster(GtkWidget *blendw, dt_iop_module_t *module)
 
     bd->raster_combo = dt_bauhaus_combobox_new(module);
     dt_bauhaus_combobox_add(bd->raster_combo, _("no mask used"));
-    g_signal_connect(G_OBJECT(bd->raster_combo), "value-changed",
+    g_signal_connect(bd->raster_combo, "value-changed",
                      G_CALLBACK(_raster_value_changed_callback), module);
     dt_bauhaus_combobox_add_populate_fct(bd->raster_combo, _raster_combo_populate);
 
@@ -3476,7 +3477,7 @@ void dt_iop_gui_init_blending(GtkWidget *iopw,
     gtk_widget_set_tooltip_text(presets_button, _("blending options"));
     if(bd->blendif_support)
     {
-      g_signal_connect(G_OBJECT(presets_button), "button-press-event",
+      g_signal_connect(GTK_BUTTON(presets_button), "button-press-event",
                        G_CALLBACK(_blendif_options_callback), module);
     }
     else
@@ -3524,7 +3525,7 @@ void dt_iop_gui_init_blending(GtkWidget *iopw,
                                           dt_develop_blend_mode_names, -1, -1);
     gtk_widget_set_tooltip_text(bd->blend_modes_combo, _("choose blending mode"));
 
-    g_signal_connect(G_OBJECT(bd->blend_modes_combo), "value-changed",
+    g_signal_connect(bd->blend_modes_combo, "value-changed",
                      G_CALLBACK(_blendop_blend_mode_callback), bd);
     dt_gui_add_help_link(GTK_WIDGET(bd->blend_modes_combo),
                          "masks_blending_op");
@@ -3565,7 +3566,7 @@ void dt_iop_gui_init_blending(GtkWidget *iopw,
        N_("combine masks"),
        dt_develop_combine_masks_names, NULL,
        _("how to combine individual drawn mask and different channels of parametric mask"));
-    g_signal_connect(G_OBJECT(bd->masks_combine_combo), "value-changed",
+    g_signal_connect(bd->masks_combine_combo, "value-changed",
                      G_CALLBACK(_blendop_masks_combine_callback), bd);
     dt_gui_add_help_link(GTK_WIDGET(bd->masks_combine_combo),
                          "masks_combined");
@@ -3578,7 +3579,7 @@ void dt_iop_gui_init_blending(GtkWidget *iopw,
        _("adjust the threshold for the details mask (using raw data),\n"
          "positive values select areas with strong details,\n"
          "negative values select flat areas"));
-    g_signal_connect(G_OBJECT(bd->details_slider), "value-changed",
+    g_signal_connect(bd->details_slider, "value-changed",
                      G_CALLBACK(_blendop_blendif_details_callback), bd);
 
     bd->masks_feathering_guide_combo = _combobox_new_from_list
@@ -3596,7 +3597,7 @@ void dt_iop_gui_init_blending(GtkWidget *iopw,
     dt_bauhaus_slider_set_format(bd->feathering_radius_slider, _(" px"));
     gtk_widget_set_tooltip_text(bd->feathering_radius_slider,
                                 _("spatial radius of feathering"));
-    g_signal_connect(G_OBJECT(bd->feathering_radius_slider), "value-changed",
+    g_signal_connect(bd->feathering_radius_slider, "value-changed",
                      G_CALLBACK(_blendop_blendif_feathering_callback), bd);
 
     bd->blur_radius_slider = dt_bauhaus_slider_new_with_range(module, 0.0, 100.0, 0, 0.0, 1);
@@ -3605,7 +3606,7 @@ void dt_iop_gui_init_blending(GtkWidget *iopw,
     dt_bauhaus_slider_set_format(bd->blur_radius_slider, _(" px"));
     gtk_widget_set_tooltip_text(bd->blur_radius_slider,
                                 _("radius for gaussian blur of blend mask"));
-    g_signal_connect(G_OBJECT(bd->blur_radius_slider), "value-changed",
+    g_signal_connect(bd->blur_radius_slider, "value-changed",
                      G_CALLBACK(_blendop_blendif_feathering_callback), bd);
 
     bd->brightness_slider = dt_bauhaus_slider_new_with_range(module, -1.0, 1.0, 0, 0.0, 2);
diff --git a/src/develop/imageop.c b/src/develop/imageop.c
index 33f49acfc94c..c5dd86eef8b6 100644
--- a/src/develop/imageop.c
+++ b/src/develop/imageop.c
@@ -476,7 +476,7 @@ static void _header_menu_deactivate_callback(GtkMenuShell *menushell,
   dt_iop_show_hide_header_buttons(module, NULL, FALSE, FALSE);
 }
 
-static void _gui_delete_callback(GtkButton *button, dt_iop_module_t *module)
+static void _gui_delete_callback(GtkWidget *button, dt_iop_module_t *module)
 {
   dt_develop_t *dev = module->dev;
 
@@ -628,7 +628,7 @@ dt_iop_module_t *dt_iop_gui_get_next_visible_module(const dt_iop_module_t *modul
   return next;
 }
 
-static void _gui_movedown_callback(GtkButton *button, dt_iop_module_t *module)
+static void _gui_movedown_callback(GtkWidget *button, dt_iop_module_t *module)
 {
   dt_ioppr_check_iop_order(module->dev, 0, "dt_iop_gui_movedown_callback begin");
 
@@ -663,7 +663,7 @@ static void _gui_movedown_callback(GtkButton *button, dt_iop_module_t *module)
   DT_CONTROL_SIGNAL_RAISE(DT_SIGNAL_DEVELOP_MODULE_MOVED);
 }
 
-static void _gui_moveup_callback(GtkButton *button, dt_iop_module_t *module)
+static void _gui_moveup_callback(GtkWidget *button, dt_iop_module_t *module)
 {
   dt_ioppr_check_iop_order(module->dev, 0, "dt_iop_gui_moveup_callback begin");
 
@@ -795,7 +795,7 @@ dt_iop_module_t *dt_iop_gui_duplicate(dt_iop_module_t *base,
   return module;
 }
 
-static void _gui_copy_callback(GtkButton *button, dt_iop_module_t *base)
+static void _gui_copy_callback(GtkWidget *button, dt_iop_module_t *base)
 {
   dt_iop_module_t *module = dt_iop_gui_duplicate(base, FALSE);
 
@@ -806,7 +806,7 @@ static void _gui_copy_callback(GtkButton *button, dt_iop_module_t *base)
     dt_iop_gui_rename_module(module);
 }
 
-static void _gui_duplicate_callback(GtkButton *button, dt_iop_module_t *base)
+static void _gui_duplicate_callback(GtkWidget *button, dt_iop_module_t *base)
 {
   dt_iop_module_t *module = dt_iop_gui_duplicate(base, TRUE);
 
@@ -914,7 +914,7 @@ void dt_iop_gui_rename_module(dt_iop_module_t *module)
   g_signal_connect(entry, "focus-out-event",
                    G_CALLBACK(_rename_module_key_press), module);
   g_signal_connect(entry, "style-updated",
-                   G_CALLBACK(_rename_module_resize), module);
+                   G_CALLBACK((GtkCallback)_rename_module_resize), (gpointer)module);
   g_signal_connect(entry, "changed",
                    G_CALLBACK(_rename_module_resize), module);
   g_signal_connect(entry, "enter-notify-event",
@@ -927,7 +927,7 @@ void dt_iop_gui_rename_module(dt_iop_module_t *module)
   gtk_widget_grab_focus(entry);
 }
 
-static void _gui_rename_callback(GtkButton *button,
+static void _gui_rename_callback(GtkWidget *button,
                                  dt_iop_module_t *module)
 {
   dt_iop_gui_rename_module(module);
@@ -978,7 +978,7 @@ static gboolean _gui_multiinstance_callback(GtkButton *button,
   if(event && event->button == GDK_BUTTON_SECONDARY)
   {
     if(!(module->flags() & IOP_FLAGS_ONE_INSTANCE))
-      _gui_copy_callback(button, module);
+      _gui_copy_callback(NULL, module);
     return TRUE;
   }
   else if(event && event->button == GDK_BUTTON_MIDDLE)
@@ -994,46 +994,46 @@ static gboolean _gui_multiinstance_callback(GtkButton *button,
 
   item = gtk_menu_item_new_with_label(_("new instance"));
   // gtk_widget_set_tooltip_text(item, _("add a new instance of this module to the pipe"));
-  g_signal_connect(G_OBJECT(item), "activate",
+  g_signal_connect(item, "activate",
                    G_CALLBACK(_gui_copy_callback), module);
   gtk_widget_set_sensitive(item, multi_show.new);
   gtk_menu_shell_append(menu, item);
 
   item = gtk_menu_item_new_with_label(_("duplicate instance"));
   // gtk_widget_set_tooltip_text(item, _("add a copy of this instance to the pipe"));
-  g_signal_connect(G_OBJECT(item), "activate",
+  g_signal_connect(item, "activate",
                    G_CALLBACK(_gui_duplicate_callback), module);
   gtk_widget_set_sensitive(item, multi_show.new);
   gtk_menu_shell_append(menu, item);
 
   item = gtk_menu_item_new_with_label(_("move up"));
   // gtk_widget_set_tooltip_text(item, _("move this instance up"));
-  g_signal_connect(G_OBJECT(item), "activate",
+  g_signal_connect(item, "activate",
                    G_CALLBACK(_gui_moveup_callback), module);
   gtk_widget_set_sensitive(item, multi_show.up);
   gtk_menu_shell_append(menu, item);
 
   item = gtk_menu_item_new_with_label(_("move down"));
   // gtk_widget_set_tooltip_text(item, _("move this instance down"));
-  g_signal_connect(G_OBJECT(item), "activate",
+  g_signal_connect(item, "activate",
                    G_CALLBACK(_gui_movedown_callback), module);
   gtk_widget_set_sensitive(item, multi_show.down);
   gtk_menu_shell_append(menu, item);
 
   item = gtk_menu_item_new_with_label(_("delete"));
   // gtk_widget_set_tooltip_text(item, _("delete this instance"));
-  g_signal_connect(G_OBJECT(item), "activate",
+  g_signal_connect(item, "activate",
                    G_CALLBACK(_gui_delete_callback), module);
   gtk_widget_set_sensitive(item, multi_show.close);
   gtk_menu_shell_append(menu, item);
 
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), gtk_separator_menu_item_new());
   item = gtk_menu_item_new_with_label(_("rename"));
-  g_signal_connect(G_OBJECT(item), "activate",
+  g_signal_connect(item, "activate",
                    G_CALLBACK(_gui_rename_callback), module);
   gtk_menu_shell_append(menu, item);
 
-  g_signal_connect(G_OBJECT(menu), "deactivate",
+  g_signal_connect(menu, "deactivate",
                    G_CALLBACK(_header_menu_deactivate_callback), module);
 
   dt_gui_menu_popup(GTK_MENU(menu), GTK_WIDGET(button),
@@ -2311,7 +2311,7 @@ static gboolean _presets_popup_callback(GtkButton *button,
 
   GtkMenu *menu = dt_gui_presets_popup_menu_show_for_module(module);
 
-  g_signal_connect(G_OBJECT(menu), "deactivate",
+  g_signal_connect(GTK_MENU_SHELL(menu), "deactivate",
                    G_CALLBACK(_header_menu_deactivate_callback), module);
 
   dt_gui_menu_popup(menu,
@@ -2531,9 +2531,8 @@ void dt_iop_gui_update_expanded(dt_iop_module_t *module)
 
 static gboolean _iop_plugin_body_button_press(GtkWidget *w,
                                               GdkEventButton *e,
-                                              gpointer user_data)
+                                              dt_iop_module_t *module)
 {
-  dt_iop_module_t *module = (dt_iop_module_t *)user_data;
   if(e->button == GDK_BUTTON_PRIMARY)
   {
     dt_iop_request_focus(module);
@@ -2550,13 +2549,11 @@ static gboolean _iop_plugin_body_button_press(GtkWidget *w,
 
 static gboolean _iop_plugin_header_button_release(GtkWidget *w,
                                                   GdkEventButton *e,
-                                                  gpointer user_data)
+                                                  dt_iop_module_t *module)
 {
   if(e->type == GDK_2BUTTON_PRESS || e->type == GDK_3BUTTON_PRESS) return TRUE;
   if(GTK_IS_BUTTON(gtk_get_event_widget((GdkEvent*)e))) return FALSE;
 
-  dt_iop_module_t *module = (dt_iop_module_t *)user_data;
-
   if(e->button == GDK_BUTTON_PRIMARY)
   {
     if(dt_modifier_is(e->state, GDK_SHIFT_MASK | GDK_CONTROL_MASK))
@@ -2748,7 +2745,7 @@ gboolean dt_iop_show_hide_header_buttons(dt_iop_module_t *module,
       GtkWidget *space = gtk_drawing_area_new();
       gtk_box_pack_end(GTK_BOX(header), space, TRUE, TRUE, 0);
       gtk_widget_show(space);
-      g_signal_connect(G_OBJECT(space), "size-allocate",
+      g_signal_connect(space, "size-allocate",
                        G_CALLBACK(_header_size_callback), header);
     }
   }
@@ -2851,9 +2848,9 @@ void dt_iop_add_remove_mask_indicator(dt_iop_module_t *module, gboolean add)
   {
     module->mask_indicator = dtgtk_togglebutton_new(dtgtk_cairo_paint_showmask, 0, NULL);
     dt_gui_add_class(module->mask_indicator, "dt_transparent_background");
-    g_signal_connect(G_OBJECT(module->mask_indicator), "toggled",
+    g_signal_connect(GTK_TOGGLE_BUTTON(module->mask_indicator), "toggled",
                      G_CALLBACK(_display_mask_indicator_callback), module);
-    g_signal_connect(G_OBJECT(module->mask_indicator), "query-tooltip",
+    g_signal_connect(module->mask_indicator, "query-tooltip",
                      G_CALLBACK(_mask_indicator_tooltip), module);
     gtk_widget_set_has_tooltip(module->mask_indicator, TRUE);
     gtk_widget_set_sensitive(module->mask_indicator, module->enabled);
@@ -2901,10 +2898,8 @@ gboolean _iop_tooltip_callback(GtkWidget *widget,
                                const gint y,
                                const gboolean keyboard_mode,
                                GtkTooltip *tooltip,
-                               gpointer user_data)
+                               dt_iop_module_t *module)
 {
-  dt_iop_module_t *module = (dt_iop_module_t *)user_data;
-
   const char **des = module->description(module);
 
   if(!des) return FALSE;
@@ -2953,7 +2948,7 @@ gboolean _iop_tooltip_callback(GtkWidget *widget,
 
   gtk_box_pack_start(GTK_BOX(vbox), grid, FALSE, FALSE, 0);
 
-  g_signal_connect(G_OBJECT(vbox), "size-allocate",
+  g_signal_connect(vbox, "size-allocate",
                    G_CALLBACK(_iop_tooltip_reposition), module->header);
 
   return dt_shortcut_tooltip_callback(widget, x, y, keyboard_mode, tooltip, vbox);
@@ -2965,7 +2960,7 @@ GtkWidget *dt_iop_gui_header_button(dt_iop_module_t *module,
                                     GtkWidget *header)
 {
   GtkWidget *button;
-  gpointer callback = _gui_multiinstance_callback;
+  gboolean(*callback)(GtkButton*, GdkEventButton*, dt_iop_module_t*) = _gui_multiinstance_callback;
 
   if(element == DT_ACTION_ELEMENT_ENABLE)
   {
@@ -2981,7 +2976,7 @@ GtkWidget *dt_iop_gui_header_button(dt_iop_module_t *module,
     gtk_widget_set_tooltip_text(button, tooltip);
     gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(button), module->enabled);
 
-    g_signal_connect(button, "toggled", G_CALLBACK(_gui_off_callback), module);
+    g_signal_connect(GTK_TOGGLE_BUTTON(button), "toggled", G_CALLBACK(_gui_off_callback), module);
     gtk_box_pack_start(GTK_BOX(header), button, FALSE, FALSE, 0);
   }
   else
@@ -3005,7 +3000,7 @@ GtkWidget *dt_iop_gui_header_button(dt_iop_module_t *module,
   g_signal_connect(button, "enter-notify-event",
                    G_CALLBACK(_header_enter_notify_callback),
                    GINT_TO_POINTER(element));
-  g_signal_connect(button, "button-press-event", G_CALLBACK(callback), module);
+  g_signal_connect(GTK_BUTTON(button), "button-press-event", G_CALLBACK(callback), module);
   dt_action_define(&module->so->actions, NULL, NULL, button, NULL);
   gtk_widget_show(button);
 
@@ -3122,21 +3117,21 @@ void dt_iop_gui_set_expander(dt_iop_module_t *module)
   module->header = header;
 
   /* setup the header box */
-  g_signal_connect(G_OBJECT(header_evb), "button-release-event",
+  g_signal_connect(header_evb, "button-release-event",
                    G_CALLBACK(_iop_plugin_header_button_release), module);
   gtk_widget_add_events(header_evb, GDK_POINTER_MOTION_MASK);
-  g_signal_connect(G_OBJECT(header_evb), "enter-notify-event",
+  g_signal_connect(header_evb, "enter-notify-event",
                    G_CALLBACK(_header_motion_notify_show_callback), module);
-  g_signal_connect(G_OBJECT(header_evb), "leave-notify-event",
+  g_signal_connect(header_evb, "leave-notify-event",
                    G_CALLBACK(_header_motion_notify_hide_callback), module);
 
   /* connect mouse button callbacks for focus and presets */
-  g_signal_connect(G_OBJECT(body_evb), "button-press-event",
+  g_signal_connect(body_evb, "button-press-event",
                    G_CALLBACK(_iop_plugin_body_button_press), module);
   gtk_widget_add_events(body_evb, GDK_POINTER_MOTION_MASK);
-  g_signal_connect(G_OBJECT(body_evb), "enter-notify-event",
+  g_signal_connect(body_evb, "enter-notify-event",
                    G_CALLBACK(_header_motion_notify_show_callback), module);
-  g_signal_connect(G_OBJECT(body_evb), "leave-notify-event",
+  g_signal_connect(body_evb, "leave-notify-event",
                    G_CALLBACK(_header_motion_notify_hide_callback), module);
 
   /*
diff --git a/src/develop/imageop_gui.c b/src/develop/imageop_gui.c
index 1b11d6e1d29d..56d402600d52 100644
--- a/src/develop/imageop_gui.c
+++ b/src/develop/imageop_gui.c
@@ -268,7 +268,7 @@ GtkWidget *dt_iop_togglebutton_new(dt_iop_module_t *self, const char *section, c
                                    DTGTKCairoPaintIconFunc paint, GtkWidget *box)
 {
   GtkWidget *w = dtgtk_togglebutton_new(paint, 0, NULL);
-  g_signal_connect(G_OBJECT(w), "button-press-event", callback, self);
+  g_signal_connect(w, "button-press-event", G_CALLBACK((gboolean(*)(GtkWidget*,GdkEventButton*, dt_iop_module_t*))callback), self);
 
   if(!ctrl_label)
     gtk_widget_set_tooltip_text(w, _(label));
@@ -304,7 +304,7 @@ GtkWidget *dt_iop_button_new(dt_iop_module_t *self, const gchar *label,
     gtk_label_set_ellipsize(GTK_LABEL(gtk_bin_get_child(GTK_BIN(button))), PANGO_ELLIPSIZE_END);
   }
 
-  g_signal_connect(G_OBJECT(button), "clicked", callback, (gpointer)self);
+  g_signal_connect(button, "clicked", G_CALLBACK((GtkCallback)callback), (gpointer)self);
 
   dt_action_t *ac = dt_action_define_iop(self, NULL, label, button, &dt_action_def_button);
     dt_shortcut_register(ac, 0, 0, accel_key, mods);
diff --git a/src/dtgtk/culling.c b/src/dtgtk/culling.c
index f057a1d55fd4..32c3f95d171c 100644
--- a/src/dtgtk/culling.c
+++ b/src/dtgtk/culling.c
@@ -540,11 +540,9 @@ static void _toggle_zoom_all(dt_culling_t *table,
 }
 
 static gboolean _event_scroll(GtkWidget *widget,
-                              GdkEvent *event,
-                              gpointer user_data)
+                              GdkEventScroll *e,
+                              dt_culling_t *table)
 {
-  GdkEventScroll *e = (GdkEventScroll *)event;
-  dt_culling_t *table = (dt_culling_t *)user_data;
   int delta;
 
   if(dt_gui_get_scroll_unit_delta(e, &delta))
@@ -583,9 +581,8 @@ static gboolean _event_draw(GtkWidget *widget, cairo_t *cr, gpointer user_data)
 
 static gboolean _event_leave_notify(GtkWidget *widget,
                                     GdkEventCrossing *event,
-                                    gpointer user_data)
+                                    dt_culling_t *table)
 {
-  dt_culling_t *table = (dt_culling_t *)user_data;
   // if the leaving cause is the hide of the widget, no mouseover change
   if(!gtk_widget_is_visible(widget))
   {
@@ -607,7 +604,7 @@ static gboolean _event_leave_notify(GtkWidget *widget,
 
 static gboolean _event_enter_notify(GtkWidget *widget,
                                     GdkEventCrossing *event,
-                                    gpointer user_data)
+                                    dt_culling_t *table)
 {
   // we only handle the case where we enter thumbtable from an
   // inferior (a thumbnail) this is when the mouse enter an "empty"
@@ -620,10 +617,8 @@ static gboolean _event_enter_notify(GtkWidget *widget,
 
 static gboolean _event_button_press(GtkWidget *widget,
                                     GdkEventButton *event,
-                                    gpointer user_data)
+                                    dt_culling_t *table)
 {
-  dt_culling_t *table = (dt_culling_t *)user_data;
-
   if(event->button == GDK_BUTTON_PRIMARY && event->type == GDK_BUTTON_PRESS)
   {
     // make sure any edition field loses the focus
@@ -741,9 +736,8 @@ static gboolean _event_motion_notify(GtkWidget *widget,
 
 static gboolean _event_button_release(GtkWidget *widget,
                                       GdkEventButton *event,
-                                      gpointer user_data)
+                                      dt_culling_t *table)
 {
-  dt_culling_t *table = (dt_culling_t *)user_data;
   table->panning = FALSE;
 
   const dt_imgid_t overid = dt_control_get_mouse_over_id();
@@ -965,19 +959,19 @@ dt_culling_t *dt_culling_new(dt_culling_mode_t mode)
   gtk_widget_set_app_paintable(table->widget, TRUE);
   gtk_widget_set_can_focus(table->widget, TRUE);
 
-  g_signal_connect(G_OBJECT(table->widget), "scroll-event",
+  g_signal_connect(table->widget, "scroll-event",
                    G_CALLBACK(_event_scroll), table);
-  g_signal_connect(G_OBJECT(table->widget), "draw",
+  g_signal_connect(table->widget, "draw",
                    G_CALLBACK(_event_draw), table);
-  g_signal_connect(G_OBJECT(table->widget), "leave-notify-event",
+  g_signal_connect(table->widget, "leave-notify-event",
                    G_CALLBACK(_event_leave_notify), table);
-  g_signal_connect(G_OBJECT(table->widget), "enter-notify-event",
+  g_signal_connect(table->widget, "enter-notify-event",
                    G_CALLBACK(_event_enter_notify), table);
-  g_signal_connect(G_OBJECT(table->widget), "button-press-event",
+  g_signal_connect(table->widget, "button-press-event",
                    G_CALLBACK(_event_button_press), table);
-  g_signal_connect(G_OBJECT(table->widget), "motion-notify-event",
+  g_signal_connect(table->widget, "motion-notify-event",
                    G_CALLBACK(_event_motion_notify), table);
-  g_signal_connect(G_OBJECT(table->widget), "button-release-event",
+  g_signal_connect(table->widget, "button-release-event",
                    G_CALLBACK(_event_button_release), table);
 
   // we register globals signals
diff --git a/src/dtgtk/expander.c b/src/dtgtk/expander.c
index 543816e38e83..4216c66a8298 100644
--- a/src/dtgtk/expander.c
+++ b/src/dtgtk/expander.c
@@ -167,12 +167,12 @@ static gboolean _expander_scroll(GtkWidget *widget, GdkFrameClock *frame_clock,
   return G_SOURCE_REMOVE;
 }
 
-static void _expander_resize(GtkWidget *widget, GdkRectangle *allocation, gpointer user_data)
+static void _expander_resize(GtkWidget *widget, GdkRectangle *allocation, GtkWidget *frame)
 {
 
   if(widget == _scroll_widget ||
      _drop_widget ? widget != _drop_widget :
-     ((!(gtk_widget_get_state_flags(user_data) & GTK_STATE_FLAG_SELECTED) ||
+     ((!(gtk_widget_get_state_flags(frame) & GTK_STATE_FLAG_SELECTED) ||
        gtk_widget_get_allocated_height(widget) == _start_pos.height) &&
       (!darktable.lib->gui_module || darktable.lib->gui_module->expander != widget)))
     return;
@@ -288,7 +288,7 @@ GtkWidget *dtgtk_expander_new(GtkWidget *header, GtkWidget *body)
   g_signal_connect(expander->header_evb, "drag-begin", G_CALLBACK(_expander_drag_begin), NULL);
   g_signal_connect(expander->header_evb, "drag-end", G_CALLBACK(_expander_drag_end), NULL);
   g_signal_connect(expander, "drag-leave", G_CALLBACK(_expander_drag_leave), NULL);
-  g_signal_connect(expander, "size-allocate", G_CALLBACK(_expander_resize), frame);
+  g_signal_connect(GTK_WIDGET(expander), "size-allocate", G_CALLBACK(_expander_resize), frame);
 
   return GTK_WIDGET(expander);
 }
diff --git a/src/dtgtk/range.c b/src/dtgtk/range.c
index 4fae45590752..1c8cb1082d27 100644
--- a/src/dtgtk/range.c
+++ b/src/dtgtk/range.c
@@ -115,10 +115,9 @@ typedef enum _range_signal
 } _range_signal;
 static guint _signals[LAST_SIGNAL] = { 0 };
 
-static void _dt_pref_changed(gpointer instance, gpointer user_data)
+static void _dt_pref_changed(GtkWidget *widget, GtkDarktableRangeSelect *range)
 {
-  if(!user_data) return;
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
+  if(!range) return;
 
   GtkStyleContext *context = gtk_widget_get_style_context(GTK_WIDGET(range->band));
   GtkStateFlags state = gtk_widget_get_state_flags(range->band);
@@ -752,7 +751,7 @@ static void _popup_date_tree_row_activated(GtkTreeView *self, GtkTreePath *path,
   gtk_widget_activate(pop->ok_btn);
 }
 
-static void _popup_date_tree_selection_change(GtkTreeView *self, GtkDarktableRangeSelect *range)
+static void _popup_date_tree_selection_change(GtkTreeSelection *self, GtkDarktableRangeSelect *range)
 {
   if(!range->date_popup || range->date_popup->internal_change) return;
   _range_date_popup *pop = range->date_popup;
@@ -937,7 +936,7 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   // the type of date selection
   pop->type = dt_bauhaus_combobox_new(NULL);
   dt_bauhaus_widget_set_label(pop->type, NULL, _("date type"));
-  g_signal_connect(G_OBJECT(pop->type), "value-changed", G_CALLBACK(_popup_date_type_changed), range);
+  g_signal_connect(pop->type, "value-changed", G_CALLBACK(_popup_date_type_changed), range);
 
   // the label to explain the reference date for relative values
   pop->relative_label = gtk_label_new("");
@@ -953,8 +952,8 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   gtk_widget_set_no_show_all(pop->calendar, TRUE);
   gtk_widget_set_tooltip_text(pop->calendar, _("click to select date\n"
                                                "double-click to use the date directly"));
-  g_signal_connect(G_OBJECT(pop->calendar), "day_selected", G_CALLBACK(_popup_date_changed), range);
-  g_signal_connect(G_OBJECT(pop->calendar), "day_selected-double-click",
+  g_signal_connect(pop->calendar, "day_selected", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->calendar, "day_selected-double-click",
                    G_CALLBACK(_popup_date_day_selected_2click), range);
 
   // the relative date box
@@ -966,7 +965,7 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   pop->years = gtk_entry_new();
   gtk_entry_set_width_chars(GTK_ENTRY(pop->years), 3);
   gtk_widget_set_halign(pop->years, GTK_ALIGN_START);
-  g_signal_connect(G_OBJECT(pop->years), "changed", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->years, "changed", G_CALLBACK(_popup_date_changed), range);
   gtk_grid_attach(GTK_GRID(pop->relative_date_box), pop->years, 1, 0, 1, 1);
   lb = gtk_label_new(_("months: "));
   gtk_label_set_xalign(GTK_LABEL(lb), 1.0);
@@ -974,7 +973,7 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   pop->months = gtk_entry_new();
   gtk_entry_set_width_chars(GTK_ENTRY(pop->months), 3);
   gtk_widget_set_halign(pop->months, GTK_ALIGN_START);
-  g_signal_connect(G_OBJECT(pop->months), "changed", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->months, "changed", G_CALLBACK(_popup_date_changed), range);
   gtk_grid_attach(GTK_GRID(pop->relative_date_box), pop->months, 1, 1, 1, 1);
   lb = gtk_label_new(_("days: "));
   gtk_label_set_xalign(GTK_LABEL(lb), 1.0);
@@ -982,7 +981,7 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   pop->days = gtk_entry_new();
   gtk_entry_set_width_chars(GTK_ENTRY(pop->days), 3);
   gtk_widget_set_halign(pop->days, GTK_ALIGN_START);
-  g_signal_connect(G_OBJECT(pop->days), "changed", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->days, "changed", G_CALLBACK(_popup_date_changed), range);
   gtk_grid_attach(GTK_GRID(pop->relative_date_box), pop->days, 1, 2, 1, 1);
   gtk_widget_show_all(pop->relative_date_box);
   gtk_widget_set_no_show_all(pop->relative_date_box, TRUE);
@@ -993,13 +992,13 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
 
   pop->hours = gtk_entry_new();
   gtk_entry_set_width_chars(GTK_ENTRY(pop->hours), 2);
-  g_signal_connect(G_OBJECT(pop->hours), "changed", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->hours, "changed", G_CALLBACK(_popup_date_changed), range);
   pop->minutes = gtk_entry_new();
   gtk_entry_set_width_chars(GTK_ENTRY(pop->minutes), 2);
-  g_signal_connect(G_OBJECT(pop->minutes), "changed", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->minutes, "changed", G_CALLBACK(_popup_date_changed), range);
   pop->seconds = gtk_entry_new();
   gtk_entry_set_width_chars(GTK_ENTRY(pop->seconds), 2);
-  g_signal_connect(G_OBJECT(pop->seconds), "changed", G_CALLBACK(_popup_date_changed), range);
+  g_signal_connect(pop->seconds, "changed", G_CALLBACK(_popup_date_changed), range);
 
   // the treeview
   GtkTreeModel *model = GTK_TREE_MODEL(gtk_tree_store_new(DATETIME_NUM_COLS, G_TYPE_STRING, G_TYPE_UINT,
@@ -1008,8 +1007,8 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   gtk_widget_set_tooltip_text(pop->calendar, _("click to select date\n"
                                                "double-click to use the date directly"));
   gtk_tree_view_set_headers_visible(GTK_TREE_VIEW(pop->treeview), FALSE);
-  g_signal_connect(G_OBJECT(pop->treeview), "row-activated", G_CALLBACK(_popup_date_tree_row_activated), range);
-  g_signal_connect(G_OBJECT(gtk_tree_view_get_selection(GTK_TREE_VIEW(pop->treeview))), "changed",
+  g_signal_connect(pop->treeview, "row-activated", G_CALLBACK(_popup_date_tree_row_activated), range);
+  g_signal_connect(gtk_tree_view_get_selection(GTK_TREE_VIEW(pop->treeview)), "changed",
                    G_CALLBACK(_popup_date_tree_selection_change), range);
 
   GtkTreeViewColumn *col = gtk_tree_view_column_new();
@@ -1025,10 +1024,10 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   pop->now_btn = gtk_button_new_with_label(_("now"));
   gtk_widget_set_no_show_all(pop->now_btn, TRUE);
   gtk_widget_set_tooltip_text(pop->now_btn, _("set the value to always match current datetime"));
-  g_signal_connect(G_OBJECT(pop->now_btn), "clicked", G_CALLBACK(_popup_date_now_clicked), range);
+  g_signal_connect(pop->now_btn, "clicked", G_CALLBACK(_popup_date_now_clicked), range);
   pop->ok_btn = gtk_button_new_with_label(_("apply"));
   gtk_widget_set_tooltip_text(pop->ok_btn, _("set the range bound with this value"));
-  g_signal_connect(G_OBJECT(pop->ok_btn), "clicked", G_CALLBACK(_popup_date_ok_clicked), range);
+  g_signal_connect(pop->ok_btn, "clicked", G_CALLBACK(_popup_date_ok_clicked), range);
 
   GtkWidget *time = dt_gui_hbox(pop->hours, gtk_label_new(" : "), pop->minutes, gtk_label_new(" : "), pop->seconds);
   gtk_widget_set_halign(time, GTK_ALIGN_CENTER);
@@ -1045,9 +1044,8 @@ static void _popup_date_init(GtkDarktableRangeSelect *range)
   gtk_container_add(GTK_CONTAINER(pop->popup), vbox);
 }
 
-static void _popup_item_activate(GtkWidget *w, gpointer user_data)
+static void _popup_item_activate(GtkWidget *w, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   // retrieve block and source values
   GtkWidget *source = GTK_WIDGET(g_object_get_data(G_OBJECT(w), "source_widget"));
   _range_block *blo = (_range_block *)g_object_get_data(G_OBJECT(w), "range_block");
@@ -1095,7 +1093,7 @@ static GtkWidget *_popup_get_numeric_menu(GtkDarktableRangeSelect *range, GtkWid
     g_free(txt);
     g_object_set_data(G_OBJECT(smt), "range_block", blo);
     g_object_set_data(G_OBJECT(smt), "source_widget", w);
-    g_signal_connect(G_OBJECT(smt), "activate", G_CALLBACK(_popup_item_activate), range);
+    g_signal_connect(smt, "activate", G_CALLBACK(_popup_item_activate), range);
 
     gtk_menu_shell_append(pop, smt);
     nb++;
@@ -1122,7 +1120,7 @@ static GtkWidget *_popup_get_numeric_menu(GtkDarktableRangeSelect *range, GtkWid
     g_free(txt);
     g_object_set_data(G_OBJECT(smt), "range_block", blo);
     g_object_set_data(G_OBJECT(smt), "source_widget", w);
-    g_signal_connect(G_OBJECT(smt), "activate", G_CALLBACK(_popup_item_activate), range);
+    g_signal_connect(smt, "activate", G_CALLBACK(_popup_item_activate), range);
 
     gtk_menu_shell_append(pop, smt);
   }
@@ -1160,9 +1158,8 @@ static void _popup_show(GtkDarktableRangeSelect *range, GtkWidget *w)
   }
 }
 
-static gboolean _event_entry_press(GtkWidget *w, GdkEventButton *e, gpointer user_data)
+static gboolean _event_entry_press(GtkWidget *w, GdkEventButton *e, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   if(e->button == GDK_BUTTON_SECONDARY)
   {
     _popup_show(range, w);
@@ -1171,18 +1168,17 @@ static gboolean _event_entry_press(GtkWidget *w, GdkEventButton *e, gpointer use
   return FALSE;
 }
 
-static void _event_entry_activated(GtkWidget *entry, gpointer user_data)
+static void _event_entry_activated(GtkWidget *entry, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   _range_bound bound = BOUND_MIN;
   if(entry == range->entry_max) bound = BOUND_MAX;
 
   _bound_change(range, gtk_entry_get_text(GTK_ENTRY(entry)), bound);
 }
 
-static gboolean _event_entry_focus_out(GtkWidget *entry, GdkEventFocus *event, gpointer user_data)
+static gboolean _event_entry_focus_out(GtkWidget *entry, GdkEventFocus *event, GtkDarktableRangeSelect *range)
 {
-  _event_entry_activated(entry, user_data);
+  _event_entry_activated(entry, range);
   return FALSE;
 }
 
@@ -1488,9 +1484,8 @@ void dtgtk_range_select_redraw(GtkDarktableRangeSelect *range)
   gtk_widget_queue_draw(range->band);
 }
 
-static gboolean _event_band_motion(GtkWidget *widget, GdkEventMotion *event, gpointer user_data)
+static gboolean _event_band_motion(GtkWidget *widget, GdkEventMotion *event, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   range->current_x_px = event->x - range->alloc_padding.x;
 
   // if we are outside the graph, don't go further
@@ -1538,9 +1533,8 @@ static gboolean _event_band_motion(GtkWidget *widget, GdkEventMotion *event, gpo
   return TRUE;
 }
 
-static gboolean _event_band_leave(GtkWidget *w, GdkEventCrossing *e, gpointer user_data)
+static gboolean _event_band_leave(GtkWidget *w, GdkEventCrossing *e, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   range->mouse_inside = HOVER_OUTSIDE;
   dt_control_change_cursor(GDK_LEFT_PTR);
   _current_hide_popup(range);
@@ -1549,9 +1543,8 @@ static gboolean _event_band_leave(GtkWidget *w, GdkEventCrossing *e, gpointer us
   return TRUE;
 }
 
-static gboolean _event_band_press(GtkWidget *w, GdkEventButton *e, gpointer user_data)
+static gboolean _event_band_press(GtkWidget *w, GdkEventButton *e, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   if(e->button == GDK_BUTTON_PRIMARY && e->type == GDK_2BUTTON_PRESS)
   {
     dtgtk_range_select_set_selection(range, DT_RANGE_BOUND_MIN | DT_RANGE_BOUND_MAX, range->min_r, range->max_r,
@@ -1595,9 +1588,8 @@ static gboolean _event_band_press(GtkWidget *w, GdkEventButton *e, gpointer user
   }
   return TRUE;
 }
-static gboolean _event_band_release(GtkWidget *w, GdkEventButton *e, gpointer user_data)
+static gboolean _event_band_release(GtkWidget *w, GdkEventButton *e, GtkDarktableRangeSelect *range)
 {
-  GtkDarktableRangeSelect *range = (GtkDarktableRangeSelect *)user_data;
   if(!range->set_selection) return TRUE;
   range->select_max_r = _graph_value_from_pos(range, e->x - range->alloc_padding.x, TRUE);
   const double min_pos_px = _graph_value_to_pos(range, range->select_min_r);
@@ -1667,12 +1659,12 @@ GtkWidget *dtgtk_range_select_new(const gchar *property, const gboolean show_ent
   range->band = gtk_drawing_area_new();
   gtk_widget_set_events(range->band, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK | GDK_STRUCTURE_MASK
                                          | GDK_LEAVE_NOTIFY_MASK | GDK_POINTER_MOTION_MASK);
-  g_signal_connect(G_OBJECT(range->band), "draw", G_CALLBACK(_event_band_draw), range);
-  g_signal_connect(G_OBJECT(range->band), "button-press-event", G_CALLBACK(_event_band_press), range);
-  g_signal_connect(G_OBJECT(range->band), "button-release-event", G_CALLBACK(_event_band_release), range);
-  g_signal_connect(G_OBJECT(range->band), "motion-notify-event", G_CALLBACK(_event_band_motion), range);
-  g_signal_connect(G_OBJECT(range->band), "leave-notify-event", G_CALLBACK(_event_band_leave), range);
-  g_signal_connect(G_OBJECT(range->band), "style-updated", G_CALLBACK(_dt_pref_changed), range);
+  g_signal_connect(range->band, "draw", G_CALLBACK(_event_band_draw), range);
+  g_signal_connect(range->band, "button-press-event", G_CALLBACK(_event_band_press), range);
+  g_signal_connect(range->band, "button-release-event", G_CALLBACK(_event_band_release), range);
+  g_signal_connect(range->band, "motion-notify-event", G_CALLBACK(_event_band_motion), range);
+  g_signal_connect(range->band, "leave-notify-event", G_CALLBACK(_event_band_leave), range);
+  g_signal_connect(range->band, "style-updated", G_CALLBACK(_dt_pref_changed), range);
   gtk_widget_set_name(GTK_WIDGET(range->band), "dt-range-band");
   gtk_widget_set_can_default(range->band, TRUE);
 
@@ -1703,17 +1695,17 @@ GtkWidget *dtgtk_range_select_new(const gchar *property, const gboolean show_ent
     range->entry_min = dt_ui_entry_new(0);
     gtk_widget_set_can_default(range->entry_min, TRUE);
     _entry_set_tooltip(range->entry_min, BOUND_MIN, range->type);
-    g_signal_connect(G_OBJECT(range->entry_min), "activate", G_CALLBACK(_event_entry_activated), range);
-    g_signal_connect(G_OBJECT(range->entry_min), "focus-out-event", G_CALLBACK(_event_entry_focus_out), range);
-    g_signal_connect(G_OBJECT(range->entry_min), "button-press-event", G_CALLBACK(_event_entry_press), range);
+    g_signal_connect(range->entry_min, "activate", G_CALLBACK(_event_entry_activated), range);
+    g_signal_connect(range->entry_min, "focus-out-event", G_CALLBACK(_event_entry_focus_out), range);
+    g_signal_connect(range->entry_min, "button-press-event", G_CALLBACK(_event_entry_press), range);
 
     range->entry_max = dt_ui_entry_new(0);
     gtk_widget_set_can_default(range->entry_max, TRUE);
     gtk_entry_set_alignment(GTK_ENTRY(range->entry_max), 1.0);
     _entry_set_tooltip(range->entry_max, BOUND_MAX, range->type);
-    g_signal_connect(G_OBJECT(range->entry_max), "activate", G_CALLBACK(_event_entry_activated), range);
-    g_signal_connect(G_OBJECT(range->entry_max), "focus-out-event", G_CALLBACK(_event_entry_focus_out), range);
-    g_signal_connect(G_OBJECT(range->entry_max), "button-press-event", G_CALLBACK(_event_entry_press), range);
+    g_signal_connect(range->entry_max, "activate", G_CALLBACK(_event_entry_activated), range);
+    g_signal_connect(range->entry_max, "focus-out-event", G_CALLBACK(_event_entry_focus_out), range);
+    g_signal_connect(range->entry_max, "button-press-event", G_CALLBACK(_event_entry_press), range);
 
     dt_gui_box_add(vbox, dt_gui_hbox(dt_gui_expand(range->entry_min), dt_gui_expand(range->entry_max)));
   }
diff --git a/src/dtgtk/resetlabel.c b/src/dtgtk/resetlabel.c
index dcc43ebbc746..b3285d89c22a 100644
--- a/src/dtgtk/resetlabel.c
+++ b/src/dtgtk/resetlabel.c
@@ -64,7 +64,7 @@ GtkWidget *dtgtk_reset_label_new(const gchar *text, dt_iop_module_t *module, voi
   gtk_widget_set_tooltip_text(GTK_WIDGET(label), _("double-click to reset"));
   gtk_container_add(GTK_CONTAINER(label), GTK_WIDGET(label->lb));
   gtk_widget_add_events(GTK_WIDGET(label), GDK_BUTTON_PRESS_MASK);
-  g_signal_connect(G_OBJECT(label), "button-press-event", G_CALLBACK(_reset_label_callback), (gpointer)NULL);
+  g_signal_connect(label, "button-press-event", G_CALLBACK(_reset_label_callback), (gpointer)NULL);
 
   return (GtkWidget *)label;
 }
diff --git a/src/dtgtk/stylemenu.c b/src/dtgtk/stylemenu.c
index 5844056cc51c..e70b3255849c 100644
--- a/src/dtgtk/stylemenu.c
+++ b/src/dtgtk/stylemenu.c
@@ -118,7 +118,7 @@ static void _build_style_submenus(GtkMenuShell *menu,
     {
       menu_data->name = g_strdup(style_name);
       menu_data->user_data = user_data;
-      g_signal_connect_data(G_OBJECT(mi), "activate",
+      g_signal_connect_data(mi, "activate",
                             G_CALLBACK(activate_callback),
                             menu_data, (GClosureNotify)_free_menu_data, 0);
     }
@@ -130,7 +130,7 @@ static void _build_style_submenus(GtkMenuShell *menu,
     {
       menu_data->name = g_strdup(style_name);
       menu_data->user_data = user_data;
-      g_signal_connect_data(G_OBJECT(mi), "button-press-event",
+      g_signal_connect_data(mi, "button-press-event",
                             G_CALLBACK(button_callback),
                             menu_data, (GClosureNotify)_free_menu_data, 0);
     }
diff --git a/src/dtgtk/thumbnail.c b/src/dtgtk/thumbnail.c
index 730ff6a92cbc..2a9c91a5f714 100644
--- a/src/dtgtk/thumbnail.c
+++ b/src/dtgtk/thumbnail.c
@@ -411,7 +411,7 @@ static void _thumb_write_extension(dt_thumbnail_t *thumb)
 
 static gboolean _event_cursor_draw(GtkWidget *widget,
                                    cairo_t *cr,
-                                   gpointer user_data)
+                                   dt_thumbnail_t *thumb)
 {
   const double w_width  = gtk_widget_get_allocated_width(widget);
   const double w_height = gtk_widget_get_allocated_height(widget);
@@ -627,11 +627,9 @@ static void _thumb_set_image_area(dt_thumbnail_t *thumb,
 
 static gboolean _event_image_draw(GtkWidget *widget,
                                   cairo_t *cr,
-                                  gpointer user_data)
+                                  dt_thumbnail_t *thumb)
 {
-  if(!user_data)
-    return TRUE;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
+  if(!thumb) return TRUE;
 
   if(!dt_is_valid_imgid(thumb->imgid))
   {
@@ -967,10 +965,9 @@ static void _thumbs_show_overlays(dt_thumbnail_t *thumb)
 
 static gboolean _event_main_motion(GtkWidget *widget,
                                    GdkEventMotion *event,
-                                   gpointer user_data)
+                                   dt_thumbnail_t *thumb)
 {
-  if(!user_data) return TRUE;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
+  if(!thumb) return TRUE;
   // first, we hide the block overlays after a delay if the mouse hasn't move
   _thumbs_show_overlays(thumb);
 
@@ -981,16 +978,15 @@ static gboolean _event_main_motion(GtkWidget *widget,
 
 static gboolean _event_rating_press(GtkWidget *widget,
                                     GdkEventButton *event,
-                                    gpointer user_data)
+                                    dt_thumbnail_t *thumb)
 {
   return TRUE;
 }
 
 static gboolean _event_rating_release(GtkWidget *widget,
                                       GdkEventButton *event,
-                                      gpointer user_data)
+                                      dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
   if(thumb->disable_actions)
     return FALSE;
   if(dtgtk_thumbnail_btn_is_hidden(widget))
@@ -1026,9 +1022,8 @@ static gboolean _event_rating_release(GtkWidget *widget,
 
 static gboolean _event_grouping_release(GtkWidget *widget,
                                         GdkEventButton *event,
-                                        gpointer user_data)
+                                        dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
   if(thumb->disable_actions)
     return FALSE;
   if(dtgtk_thumbnail_btn_is_hidden(widget))
@@ -1076,9 +1071,8 @@ static gboolean _event_grouping_release(GtkWidget *widget,
 
 static gboolean _event_audio_release(GtkWidget *widget,
                                      GdkEventButton *event,
-                                     gpointer user_data)
+                                     dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
   if(thumb->disable_actions)
     return FALSE;
   if(dtgtk_thumbnail_btn_is_hidden(widget))
@@ -1106,10 +1100,9 @@ static gboolean _event_audio_release(GtkWidget *widget,
 // this is called each time the images info change
 static void _dt_image_info_changed_callback(gpointer instance,
                                             const gpointer imgs,
-                                            gpointer user_data)
+                                            dt_thumbnail_t *thumb)
 {
-  if(!user_data || !imgs) return;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
+  if(!thumb || !imgs) return;
   for(const GList *i = imgs; i; i = g_list_next(i))
   {
     if(GPOINTER_TO_INT(i->data) == thumb->imgid)
@@ -1127,10 +1120,9 @@ static void _dt_collection_changed_callback(gpointer instance,
                                             dt_collection_properties_t changed_property,
                                             const gpointer imgs,
                                             const int next,
-                                            gpointer user_data)
+                                            dt_thumbnail_t *thumb)
 {
-  if(!user_data || !imgs) return;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
+  if(!thumb || !imgs) return;
   for(const GList *i = imgs; i; i = g_list_next(i))
   {
     if(GPOINTER_TO_INT(i->data) == thumb->imgid)
@@ -1162,20 +1154,17 @@ void dt_thumbnail_update_selection(dt_thumbnail_t *thumb)
 }
 
 static void _dt_selection_changed_callback(gpointer instance,
-                                           gpointer user_data)
+                                           dt_thumbnail_t *thumb)
 {
-  if(!user_data)
+  if(!thumb)
     return;
-  dt_thumbnail_update_selection((dt_thumbnail_t *)user_data);
+  dt_thumbnail_update_selection(thumb);
 }
 
 static void _dt_active_images_callback(gpointer instance,
-                                       gpointer user_data)
+                                       dt_thumbnail_t *thumb)
 {
-  if(!user_data)
-    return;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
-
+  if(!thumb) return;
   gboolean active = FALSE;
   for(GSList *l = darktable.view_manager->active_images;
       l;
@@ -1202,10 +1191,9 @@ static void _dt_active_images_callback(gpointer instance,
 }
 
 static void _dt_preview_updated_callback(gpointer instance,
-                                         gpointer user_data)
+                                         dt_thumbnail_t *thumb)
 {
-  if(!user_data) return;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
+  if(!thumb) return;
   if(!gtk_widget_is_visible(thumb->w_main)) return;
 
   if(dt_view_get_current() == DT_VIEW_DARKROOM
@@ -1221,10 +1209,9 @@ static void _dt_preview_updated_callback(gpointer instance,
 
 static void _dt_mipmaps_updated_callback(gpointer instance,
                                          const dt_imgid_t imgid,
-                                         gpointer user_data)
+                                         dt_thumbnail_t *thumb)
 {
-  if(!user_data) return;
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
+  if(!thumb) return;
   if(dt_is_valid_imgid(imgid) && thumb->imgid != imgid) return;
 
   // we recompte the history tooltip if needed
@@ -1237,9 +1224,8 @@ static void _dt_mipmaps_updated_callback(gpointer instance,
 
 static gboolean _event_box_enter_leave(GtkWidget *widget,
                                        GdkEventCrossing *event,
-                                       gpointer user_data)
+                                       dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
   // if we leave for ancestor, that means we leave for blank thumbtable area
   if(event->type == GDK_LEAVE_NOTIFY
      && event->detail == GDK_NOTIFY_ANCESTOR)
@@ -1258,10 +1244,8 @@ static gboolean _event_box_enter_leave(GtkWidget *widget,
 
 static gboolean _event_image_enter_leave(GtkWidget *widget,
                                          GdkEventCrossing *event,
-                                         gpointer user_data)
+                                         dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
-
   // we ensure that the image has mouse over
   if(!thumb->mouse_over && event->type == GDK_ENTER_NOTIFY
      && !thumb->disable_mouseover)
@@ -1274,10 +1258,8 @@ static gboolean _event_image_enter_leave(GtkWidget *widget,
 
 static gboolean _event_btn_enter_leave(GtkWidget *widget,
                                        GdkEventCrossing *event,
-                                       gpointer user_data)
+                                       dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
-
   darktable.control->element =
     (event->type == GDK_ENTER_NOTIFY && widget == thumb->w_reject)
     ? DT_VIEW_REJECT
@@ -1300,9 +1282,8 @@ static gboolean _event_btn_enter_leave(GtkWidget *widget,
 
 static gboolean _event_star_enter(GtkWidget *widget,
                                   GdkEventCrossing *event,
-                                  gpointer user_data)
+                                  dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
   if(thumb->disable_actions) return TRUE;
   if(!thumb->mouse_over && !thumb->disable_mouseover)
     dt_control_set_mouse_over_id(thumb->imgid);
@@ -1326,9 +1307,8 @@ static gboolean _event_star_enter(GtkWidget *widget,
 }
 static gboolean _event_star_leave(GtkWidget *widget,
                                   GdkEventCrossing *event,
-                                  gpointer user_data)
+                                  dt_thumbnail_t *thumb)
 {
-  dt_thumbnail_t *thumb = (dt_thumbnail_t *)user_data;
   // if we leave for ancestor, that means we leave for blank thumbtable area
   if(event->type == GDK_LEAVE_NOTIFY
      && event->detail == GDK_NOTIFY_ANCESTOR)
@@ -1345,7 +1325,7 @@ static gboolean _event_star_leave(GtkWidget *widget,
 
 static gboolean _event_main_leave(GtkWidget *widget,
                                   GdkEventCrossing *event,
-                                  gpointer user_data)
+                                  dt_thumbnail_t *thumb)
 {
   // if we leave for ancestor, that means we leave for blank thumbtable area
   if(event->detail == GDK_NOTIFY_ANCESTOR) dt_control_set_mouse_over_id(NO_IMGID);
@@ -1358,9 +1338,9 @@ static gboolean _event_main_drag_motion(GtkWidget *widget,
                                         const gint x,
                                         const gint y,
                                         const guint time,
-                                        gpointer user_data)
+                                        dt_thumbnail_t *thumb)
 {
-  _event_main_motion(widget, NULL, user_data);
+  _event_main_motion(widget, NULL, thumb);
   return TRUE;
 }
 
@@ -1402,7 +1382,7 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     // all dragging actions take place inside thumbatble.c
     gtk_drag_dest_set(thumb->w_main, GTK_DEST_DEFAULT_MOTION,
                       target_list_all, n_targets_all, GDK_ACTION_MOVE);
-    g_signal_connect(G_OBJECT(thumb->w_main), "drag-motion",
+    g_signal_connect(thumb->w_main, "drag-motion",
                      G_CALLBACK(_event_main_drag_motion), thumb);
 
     g_object_set_data(G_OBJECT(thumb->w_main), "thumb", thumb);
@@ -1421,9 +1401,9 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
                           | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK
                           | GDK_POINTER_MOTION_MASK);
     gtk_widget_set_name(thumb->w_back, "thumb-back");
-    g_signal_connect(G_OBJECT(thumb->w_back), "motion-notify-event",
+    g_signal_connect(thumb->w_back, "motion-notify-event",
                      G_CALLBACK(_event_main_motion), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_back), "leave-notify-event",
+    g_signal_connect(thumb->w_back, "leave-notify-event",
                      G_CALLBACK(_event_main_leave), thumb);
     gtk_widget_show(thumb->w_back);
     gtk_container_add(GTK_CONTAINER(thumb->w_main), thumb->w_back);
@@ -1454,11 +1434,11 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
                           | GDK_STRUCTURE_MASK
                           | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK
                           | GDK_POINTER_MOTION_MASK);
-    g_signal_connect(G_OBJECT(evt_image), "motion-notify-event",
+    g_signal_connect(evt_image, "motion-notify-event",
                      G_CALLBACK(_event_main_motion), thumb);
-    g_signal_connect(G_OBJECT(evt_image), "enter-notify-event",
+    g_signal_connect(evt_image, "enter-notify-event",
                      G_CALLBACK(_event_image_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(evt_image), "leave-notify-event",
+    g_signal_connect(evt_image, "leave-notify-event",
                      G_CALLBACK(_event_image_enter_leave), thumb);
     gtk_widget_show(evt_image);
     gtk_overlay_add_overlay(GTK_OVERLAY(thumb->w_image_box), evt_image);
@@ -1471,15 +1451,15 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
                           | GDK_BUTTON_RELEASE_MASK | GDK_STRUCTURE_MASK
                           | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK
                           | GDK_POINTER_MOTION_MASK);
-    g_signal_connect(G_OBJECT(thumb->w_image), "draw",
+    g_signal_connect(thumb->w_image, "draw",
                      G_CALLBACK(_event_image_draw), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_image), "motion-notify-event",
+    g_signal_connect(thumb->w_image, "motion-notify-event",
                      G_CALLBACK(_event_main_motion), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_image), "enter-notify-event",
+    g_signal_connect(thumb->w_image, "enter-notify-event",
                      G_CALLBACK(_event_image_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_image), "leave-notify-event",
+    g_signal_connect(thumb->w_image, "leave-notify-event",
                      G_CALLBACK(_event_image_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_image), "style-updated",
+    g_signal_connect(thumb->w_image, "style-updated",
                      G_CALLBACK(_event_image_style_updated), thumb);
     gtk_widget_show(thumb->w_image);
     gtk_overlay_add_overlay(GTK_OVERLAY(thumb->w_image_box), thumb->w_image);
@@ -1490,7 +1470,7 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     gtk_widget_set_name(thumb->w_cursor, "thumb-cursor");
     gtk_widget_set_valign(thumb->w_cursor, GTK_ALIGN_START);
     gtk_widget_set_halign(thumb->w_cursor, GTK_ALIGN_CENTER);
-    g_signal_connect(G_OBJECT(thumb->w_cursor), "draw",
+    g_signal_connect(thumb->w_cursor, "draw",
                      G_CALLBACK(_event_cursor_draw), thumb);
     gtk_overlay_add_overlay(GTK_OVERLAY(thumb->w_main), thumb->w_cursor);
 
@@ -1502,10 +1482,10 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     // the infos background
     thumb->w_bottom_eb = gtk_event_box_new();
     gtk_widget_set_name(thumb->w_bottom_eb, "thumb-bottom");
-    g_signal_connect(G_OBJECT(thumb->w_bottom_eb), "enter-notify-event",
+    g_signal_connect(thumb->w_bottom_eb, "enter-notify-event",
                      G_CALLBACK(_event_box_enter_leave),
                      thumb);
-    g_signal_connect(G_OBJECT(thumb->w_bottom_eb), "leave-notify-event",
+    g_signal_connect(thumb->w_bottom_eb, "leave-notify-event",
                      G_CALLBACK(_event_box_enter_leave),
                      thumb);
     gtk_widget_set_valign(thumb->w_bottom_eb, GTK_ALIGN_END);
@@ -1541,13 +1521,13 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     gtk_widget_set_valign(thumb->w_reject, GTK_ALIGN_END);
     gtk_widget_set_halign(thumb->w_reject, GTK_ALIGN_START);
     gtk_widget_show(thumb->w_reject);
-    g_signal_connect(G_OBJECT(thumb->w_reject), "button-press-event",
+    g_signal_connect(thumb->w_reject, "button-press-event",
                      G_CALLBACK(_event_rating_press), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_reject), "button-release-event",
+    g_signal_connect(thumb->w_reject, "button-release-event",
                      G_CALLBACK(_event_rating_release), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_reject), "enter-notify-event",
+    g_signal_connect(thumb->w_reject, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_reject), "leave-notify-event",
+    g_signal_connect(thumb->w_reject, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_overlay_add_overlay(GTK_OVERLAY(overlays_parent), thumb->w_reject);
 
@@ -1555,13 +1535,13 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     for(int i = 0; i < MAX_STARS; i++)
     {
       thumb->w_stars[i] = dtgtk_thumbnail_btn_new(dtgtk_cairo_paint_star, 0, NULL);
-      g_signal_connect(G_OBJECT(thumb->w_stars[i]), "enter-notify-event",
+      g_signal_connect(thumb->w_stars[i], "enter-notify-event",
                        G_CALLBACK(_event_star_enter), thumb);
-      g_signal_connect(G_OBJECT(thumb->w_stars[i]), "leave-notify-event",
+      g_signal_connect(thumb->w_stars[i], "leave-notify-event",
                        G_CALLBACK(_event_star_leave), thumb);
-      g_signal_connect(G_OBJECT(thumb->w_stars[i]), "button-press-event",
+      g_signal_connect(thumb->w_stars[i], "button-press-event",
                        G_CALLBACK(_event_rating_press), thumb);
-      g_signal_connect(G_OBJECT(thumb->w_stars[i]), "button-release-event",
+      g_signal_connect(thumb->w_stars[i], "button-release-event",
                        G_CALLBACK(_event_rating_release),
                        thumb);
       gtk_widget_set_name(thumb->w_stars[i], "thumb-star");
@@ -1582,9 +1562,9 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     gtk_widget_set_valign(thumb->w_color, GTK_ALIGN_END);
     gtk_widget_set_halign(thumb->w_color, GTK_ALIGN_END);
     gtk_widget_set_no_show_all(thumb->w_color, TRUE);
-    g_signal_connect(G_OBJECT(thumb->w_color), "enter-notify-event",
+    g_signal_connect(thumb->w_color, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_color), "leave-notify-event",
+    g_signal_connect(thumb->w_color, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_overlay_add_overlay(GTK_OVERLAY(overlays_parent), thumb->w_color);
 
@@ -1595,10 +1575,10 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     gtk_widget_set_valign(thumb->w_local_copy, GTK_ALIGN_START);
     gtk_widget_set_halign(thumb->w_local_copy, GTK_ALIGN_END);
     gtk_widget_set_no_show_all(thumb->w_local_copy, TRUE);
-    g_signal_connect(G_OBJECT(thumb->w_local_copy), "enter-notify-event",
+    g_signal_connect(thumb->w_local_copy, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave),
                      thumb);
-    g_signal_connect(G_OBJECT(thumb->w_local_copy), "leave-notify-event",
+    g_signal_connect(thumb->w_local_copy, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave),
                      thumb);
     gtk_overlay_add_overlay(GTK_OVERLAY(overlays_parent), thumb->w_local_copy);
@@ -1609,9 +1589,9 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     gtk_widget_set_valign(thumb->w_altered, GTK_ALIGN_START);
     gtk_widget_set_halign(thumb->w_altered, GTK_ALIGN_END);
     gtk_widget_set_no_show_all(thumb->w_altered, TRUE);
-    g_signal_connect(G_OBJECT(thumb->w_altered), "enter-notify-event",
+    g_signal_connect(thumb->w_altered, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_altered), "leave-notify-event",
+    g_signal_connect(thumb->w_altered, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_overlay_add_overlay(GTK_OVERLAY(overlays_parent), thumb->w_altered);
 
@@ -1621,20 +1601,20 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     gtk_widget_set_valign(thumb->w_tags, GTK_ALIGN_START);
     gtk_widget_set_halign(thumb->w_tags, GTK_ALIGN_END);
     gtk_widget_set_no_show_all(thumb->w_tags, TRUE);
-    g_signal_connect(G_OBJECT(thumb->w_tags), "enter-notify-event",
+    g_signal_connect(thumb->w_tags, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_tags), "leave-notify-event",
+    g_signal_connect(thumb->w_tags, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_overlay_add_overlay(GTK_OVERLAY(overlays_parent), thumb->w_tags);
 
     // the group bouton
     thumb->w_group = dtgtk_thumbnail_btn_new(dtgtk_cairo_paint_grouping, 0, NULL);
     gtk_widget_set_name(thumb->w_group, "thumb-group-audio");
-    g_signal_connect(G_OBJECT(thumb->w_group), "button-release-event",
+    g_signal_connect(thumb->w_group, "button-release-event",
                      G_CALLBACK(_event_grouping_release), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_group), "enter-notify-event",
+    g_signal_connect(thumb->w_group, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_group), "leave-notify-event",
+    g_signal_connect(thumb->w_group, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_widget_set_valign(thumb->w_group, GTK_ALIGN_START);
     gtk_widget_set_halign(thumb->w_group, GTK_ALIGN_END);
@@ -1644,11 +1624,11 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
     // the sound icon
     thumb->w_audio = dtgtk_thumbnail_btn_new(dtgtk_cairo_paint_audio, 0, NULL);
     gtk_widget_set_name(thumb->w_audio, "thumb-group-audio");
-    g_signal_connect(G_OBJECT(thumb->w_audio), "button-release-event",
+    g_signal_connect(thumb->w_audio, "button-release-event",
                      G_CALLBACK(_event_audio_release), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_audio), "enter-notify-event",
+    g_signal_connect(thumb->w_audio, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
-    g_signal_connect(G_OBJECT(thumb->w_audio), "leave-notify-event",
+    g_signal_connect(thumb->w_audio, "leave-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_widget_set_valign(thumb->w_audio, GTK_ALIGN_START);
     gtk_widget_set_halign(thumb->w_audio, GTK_ALIGN_END);
@@ -1657,7 +1637,7 @@ GtkWidget *dt_thumbnail_create_widget(dt_thumbnail_t *thumb,
 
     // the zoom indicator
     thumb->w_zoom_eb = gtk_event_box_new();
-    g_signal_connect(G_OBJECT(thumb->w_zoom_eb), "enter-notify-event",
+    g_signal_connect(thumb->w_zoom_eb, "enter-notify-event",
                      G_CALLBACK(_event_btn_enter_leave), thumb);
     gtk_widget_set_name(thumb->w_zoom_eb, "thumb-zoom");
     gtk_widget_set_valign(thumb->w_zoom_eb, GTK_ALIGN_START);
diff --git a/src/dtgtk/thumbtable.c b/src/dtgtk/thumbtable.c
index e85e6d87203e..8859ccfd4cb3 100644
--- a/src/dtgtk/thumbtable.c
+++ b/src/dtgtk/thumbtable.c
@@ -1479,7 +1479,7 @@ static gboolean _event_button_press(GtkWidget *widget,
     if(event->x < button->x && event->x > button->x - button->width
        && event->y < button->y && event->y > button->y - button->height)
     {
-      dt_gui_show_help(NULL);
+      dt_gui_show_help(NULL, NULL);
     }
 
     return TRUE;
@@ -2461,19 +2461,19 @@ dt_thumbtable_t *dt_thumbtable_new()
   g_signal_connect(table->widget, "drag-data-received",
                    G_CALLBACK(dt_thumbtable_event_dnd_received), table);
 
-  g_signal_connect(G_OBJECT(table->widget), "scroll-event",
+  g_signal_connect(table->widget, "scroll-event",
                    G_CALLBACK(_event_scroll), table);
-  g_signal_connect(G_OBJECT(table->widget), "draw",
+  g_signal_connect(table->widget, "draw",
                    G_CALLBACK(_event_draw), table);
-  g_signal_connect(G_OBJECT(table->widget), "leave-notify-event",
+  g_signal_connect(table->widget, "leave-notify-event",
                    G_CALLBACK(_event_leave_notify), table);
-  g_signal_connect(G_OBJECT(table->widget), "enter-notify-event",
+  g_signal_connect(table->widget, "enter-notify-event",
                    G_CALLBACK(_event_enter_notify), table);
-  g_signal_connect(G_OBJECT(table->widget), "button-press-event",
+  g_signal_connect(table->widget, "button-press-event",
                    G_CALLBACK(_event_button_press), table);
-  g_signal_connect(G_OBJECT(table->widget), "motion-notify-event",
+  g_signal_connect(table->widget, "motion-notify-event",
                    G_CALLBACK(_event_motion_notify), table);
-  g_signal_connect(G_OBJECT(table->widget), "button-release-event",
+  g_signal_connect(table->widget, "button-release-event",
                    G_CALLBACK(_event_button_release), table);
 
   // we register globals signals
diff --git a/src/dtgtk/togglebutton.c b/src/dtgtk/togglebutton.c
index 5a978d2b3078..a6c8cf004901 100644
--- a/src/dtgtk/togglebutton.c
+++ b/src/dtgtk/togglebutton.c
@@ -141,7 +141,7 @@ GtkWidget *dtgtk_togglebutton_new(DTGTKCairoPaintIconFunc paint, gint paintflags
   gtk_container_add(GTK_CONTAINER(button), button->canvas);
   dt_gui_add_class(GTK_WIDGET(button), "dt_module_btn");
   gtk_widget_set_name(GTK_WIDGET(button->canvas), "button-canvas");
-  g_signal_connect(G_OBJECT(button), "toggled", G_CALLBACK(gtk_widget_queue_draw), NULL);
+  g_signal_connect(GTK_WIDGET(button), "toggled", G_CALLBACK((GtkCallback)gtk_widget_queue_draw), NULL);
   return (GtkWidget *)button;
 }
 
diff --git a/src/gui/about.c b/src/gui/about.c
index cb0295b9f493..d3f109f4026b 100644
--- a/src/gui/about.c
+++ b/src/gui/about.c
@@ -22,7 +22,7 @@
 #include "osx/osx.h"
 #endif
 
-void darktable_show_about_dialog()
+void darktable_show_about_dialog(void)
 {
   GtkWidget *dialog = gtk_about_dialog_new();
   gtk_widget_set_name (dialog, "about-dialog");
diff --git a/src/gui/about.h b/src/gui/about.h
index 9bec9cd2f330..cb26f57d2070 100644
--- a/src/gui/about.h
+++ b/src/gui/about.h
@@ -16,4 +16,4 @@
     along with darktable.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-void darktable_show_about_dialog();
+void darktable_show_about_dialog(void);
diff --git a/src/gui/accelerators.c b/src/gui/accelerators.c
index c650e17598ea..c447e875e4f4 100644
--- a/src/gui/accelerators.c
+++ b/src/gui/accelerators.c
@@ -1219,7 +1219,7 @@ gboolean dt_shortcut_tooltip_callback(GtkWidget *widget,
 
   gtk_widget_show_all(vbox);
   gtk_tooltip_set_custom(tooltip, vbox);
-  g_signal_connect(G_OBJECT(vbox), "size-allocate", G_CALLBACK(_tooltip_reposition), widget);
+  g_signal_connect(vbox, "size-allocate", G_CALLBACK(_tooltip_reposition), widget);
 
   return TRUE;
 }
@@ -1779,11 +1779,9 @@ static void _element_editing_started(GtkCellRenderer *renderer,
 static void _element_changed(GtkCellRendererCombo *combo,
                              char *path_string,
                              GtkTreeIter *new_iter,
-                             gpointer data)
+                             GtkTreeModel *model)
 {
-  dt_shortcut_t *s = _find_edited_shortcut(data, path_string);
-
-  GtkTreeModel *model = NULL;
+  dt_shortcut_t *s = _find_edited_shortcut(model, path_string);
   g_object_get(combo, "model", &model, NULL);
   GtkTreePath *path = gtk_tree_model_get_path(model, new_iter);
   const gint new_index = gtk_tree_path_get_indices(path)[0];
@@ -1902,11 +1900,9 @@ static void _effect_editing_started(GtkCellRenderer *renderer,
 static void _effect_changed(GtkCellRendererCombo *combo,
                             char *path_string,
                             GtkTreeIter *new_iter,
-                            gpointer data)
+                            GtkTreeModel *model)
 {
-  dt_shortcut_t *s = _find_edited_shortcut(data, path_string);
-
-  GtkTreeModel *model = NULL;
+  dt_shortcut_t *s = _find_edited_shortcut(model, path_string);
   g_object_get(combo, "model", &model, NULL);
   GtkTreePath *path = gtk_tree_model_get_path(model, new_iter);
   const gint new_index = s->effect = gtk_tree_path_get_indices(path)[0];
@@ -1986,18 +1982,17 @@ static void _shortcut_row_activated(GtkTreeView *tree_view,
   _grab_in_tree_view(tree_view);
 }
 
-static gboolean _view_key_pressed(GtkWidget *widget,
+static gboolean _view_key_pressed(GtkTreeView *view,
                                   GdkEventKey *event,
-                                  gpointer user_data)
+                                  GtkSearchEntry *search)
 {
-  GtkTreeView *view = GTK_TREE_VIEW(widget);
   GtkTreeSelection *selection = gtk_tree_view_get_selection(view);
 
   GtkTreeIter iter;
   GtkTreeModel *model = NULL;
   if(gtk_tree_selection_get_selected(selection, &model, &iter))
   {
-    if(!strcmp(gtk_widget_get_name(widget), "actions_view"))
+    if(!strcmp(gtk_widget_get_name(GTK_WIDGET(view)), "actions_view"))
     {
       // if control key pressed, copy lua command to clipboard (CTRL+C will work)
       if(dt_modifier_is(event->state, GDK_CONTROL_MASK))
@@ -2043,7 +2038,7 @@ static gboolean _view_key_pressed(GtkWidget *widget,
     }
   }
 
-  return dt_gui_search_start(widget, event, user_data);
+  return dt_gui_search_start(GTK_WIDGET(view), event, search);
 }
 
 static void _add_shortcuts_to_tree()
@@ -2211,7 +2206,7 @@ static gboolean _shortcut_selection_function(GtkTreeSelection *selection,
 }
 
 static void _shortcut_selection_changed(GtkTreeSelection *selection,
-                                        gpointer data)
+                                        GtkTreeView *view)
 {
   GtkTreeModel *model = NULL;
   GtkTreeIter iter;
@@ -2225,7 +2220,7 @@ static void _shortcut_selection_changed(GtkTreeSelection *selection,
   else
     _selected_shortcut = NULL;
 
-  gtk_widget_queue_draw(GTK_WIDGET(data));
+  gtk_widget_queue_draw(GTK_WIDGET(view));
 }
 
 static gboolean _action_find_and_expand(GtkTreeModel *model,
@@ -2258,11 +2253,10 @@ static gboolean _action_find_and_expand(GtkTreeModel *model,
   return FALSE;
 }
 
-static gboolean _action_view_click(GtkWidget *widget,
+static gboolean _action_view_click(GtkTreeView *view,
                                    GdkEventButton *event,
-                                   gpointer data)
+                                   gpointer user_data)
 {
-  GtkTreeView *view = GTK_TREE_VIEW(widget);
   GtkTreeModel *model = gtk_tree_view_get_model(view);
 
   if(event->button == GDK_BUTTON_PRIMARY)
@@ -2289,7 +2283,7 @@ static gboolean _action_view_click(GtkWidget *widget,
         gtk_tree_view_set_cursor(view, path, NULL, FALSE);
       }
 
-      gtk_widget_grab_focus(widget);
+      gtk_widget_grab_focus(GTK_WIDGET(view));
     }
     else
       gtk_tree_selection_unselect_all(selection);
@@ -2320,7 +2314,7 @@ static gboolean _action_view_show(GtkTreeView *view,
 }
 
 static void _action_selection_changed(GtkTreeSelection *selection,
-                                      gpointer data)
+                                      GtkTreeView *shortcuts_view)
 {
   GtkTreeIter iter;
   GtkTreeModel *model = NULL;
@@ -2337,7 +2331,6 @@ static void _action_selection_changed(GtkTreeSelection *selection,
     gtk_tree_path_free(path);
   }
 
-  GtkTreeView *shortcuts_view = GTK_TREE_VIEW(data);
   gtk_tree_model_filter_refilter(GTK_TREE_MODEL_FILTER
                                  (gtk_tree_view_get_model(shortcuts_view)));
   gtk_tree_view_expand_all(shortcuts_view);
@@ -2507,12 +2500,11 @@ static void _shortcuts_load(const gchar *shortcuts_file,
                             const dt_input_device_t load_dev,
                             const gboolean clear);
 
-static void _fallbacks_toggled(GtkToggleButton *button, gpointer data)
+static void _fallbacks_toggled(GtkWidget *button, GtkTreeView *shortcuts_view)
 {
   dt_conf_set_bool("accel/enable_fallbacks",
                    (darktable.control->enable_fallbacks = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button))));
 
-  GtkTreeView *shortcuts_view = GTK_TREE_VIEW(data);
   gtk_tree_model_filter_refilter(GTK_TREE_MODEL_FILTER
                                  (gtk_tree_view_get_model(shortcuts_view)));
 }
@@ -2570,8 +2562,8 @@ static void _restore_clicked(GtkButton *button, gpointer user_data)
   dt_shortcuts_save(NULL, FALSE);
 }
 
-static void _import_export_dev_changed(GtkComboBox *widget,
-                                       gpointer user_data)
+static void _import_export_dev_changed(GtkWidget *widget,
+                                       GtkWidget *user_data)
 {
   gint dev = gtk_combo_box_get_active(GTK_COMBO_BOX(widget));
   g_object_set_data(G_OBJECT(user_data), "device", GINT_TO_POINTER(dev));
@@ -2580,8 +2572,8 @@ static void _import_export_dev_changed(GtkComboBox *widget,
   gtk_widget_set_visible(gtk_widget_get_parent(GTK_WIDGET(user_data)), dev > 1);
 }
 
-static void _export_id_changed(GtkComboBox *widget,
-                               gpointer user_data)
+static void _export_id_changed(GtkWidget *widget,
+                               GtkWidget *user_data)
 {
   gint dev = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(widget), "device"));
   gint id = dev <= 1 ? 0 :
@@ -2671,9 +2663,9 @@ static void _export_clicked(GtkButton *button, gpointer user_data)
   g_object_unref(chooser);
 }
 
-static void _import_id_changed(GtkComboBox *widget, gpointer user_data)
+static void _import_id_changed(GtkWidget *widget, GtkWidget *user_data)
 {
-  gint id = gtk_combo_box_get_active(widget);
+  gint id = gtk_combo_box_get_active(GTK_COMBO_BOX(widget));
   gtk_combo_box_set_active(GTK_COMBO_BOX(user_data), id);
 }
 
@@ -2891,14 +2883,14 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
   g_object_unref(G_OBJECT(filtered_shortcuts));
   gtk_tree_view_set_search_column(shortcuts_view, 0); // fake column for _search_func
   gtk_tree_view_set_search_equal_func(shortcuts_view, _search_func, shortcuts_view, NULL);
-  GtkWidget *search_shortcuts = gtk_search_entry_new();
+  GtkSearchEntry *search_shortcuts = GTK_SEARCH_ENTRY(gtk_search_entry_new());
   gtk_entry_set_placeholder_text(GTK_ENTRY(search_shortcuts),
                                  _("search shortcuts list"));
   gtk_widget_set_tooltip_text(GTK_WIDGET(search_shortcuts),
                               _("incrementally search the list of shortcuts\npress up or down keys to cycle through matches"));
-  g_signal_connect(G_OBJECT(search_shortcuts), "activate",
+  g_signal_connect(search_shortcuts, "activate",
                    G_CALLBACK(dt_gui_search_stop), shortcuts_view);
-  g_signal_connect(G_OBJECT(search_shortcuts), "stop-search",
+  g_signal_connect(search_shortcuts, "stop-search",
                    G_CALLBACK(dt_gui_search_stop), shortcuts_view);
   gtk_tree_view_set_search_entry(shortcuts_view, GTK_ENTRY(search_shortcuts));
 
@@ -2906,11 +2898,11 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
                                          _shortcut_selection_function, NULL, NULL);
   g_object_set(shortcuts_view, "has-tooltip", TRUE, NULL);
   gtk_widget_set_name(GTK_WIDGET(shortcuts_view), "shortcuts_view");
-  g_signal_connect(G_OBJECT(shortcuts_view), "row-activated",
+  g_signal_connect(shortcuts_view, "row-activated",
                    G_CALLBACK(_shortcut_row_activated), filtered_shortcuts);
-  g_signal_connect(G_OBJECT(shortcuts_view), "key-press-event",
+  g_signal_connect(shortcuts_view, "key-press-event",
                    G_CALLBACK(_view_key_pressed), search_shortcuts);
-  g_signal_connect(G_OBJECT(_shortcuts_store), "row-inserted",
+  g_signal_connect(_shortcuts_store, "row-inserted",
                    G_CALLBACK(_shortcut_row_inserted), shortcuts_view);
 
   // Setting up the cell renderers
@@ -2927,7 +2919,8 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
   g_object_set(renderer, "model", elements, "text-column", 0, "has-entry", FALSE, NULL);
   g_signal_connect(renderer, "editing-started" ,
                    G_CALLBACK(_element_editing_started), filtered_shortcuts);
-  g_signal_connect(renderer, "changed", G_CALLBACK(_element_changed), filtered_shortcuts);
+  g_signal_connect(GTK_CELL_RENDERER_COMBO(renderer), "changed",
+                   G_CALLBACK(_element_changed), filtered_shortcuts);
   _add_prefs_column(shortcuts_view, renderer, _("element"), SHORTCUT_VIEW_ELEMENT);
 
   renderer = gtk_cell_renderer_combo_new();
@@ -2935,7 +2928,8 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
   g_object_set(renderer, "model", effects, "text-column", 0, "has-entry", FALSE, NULL);
   g_signal_connect(renderer, "editing-started" ,
                    G_CALLBACK(_effect_editing_started), filtered_shortcuts);
-  g_signal_connect(renderer, "changed", G_CALLBACK(_effect_changed), filtered_shortcuts);
+  g_signal_connect(GTK_CELL_RENDERER_COMBO(renderer), "changed",
+                   G_CALLBACK(_effect_changed), filtered_shortcuts);
   _add_prefs_column(shortcuts_view, renderer, _("effect"), SHORTCUT_VIEW_EFFECT);
 
   renderer = gtk_cell_renderer_spin_new();
@@ -2992,29 +2986,29 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
   g_object_unref(_actions_store);
   gtk_tree_view_set_search_column(actions_view, 1); // fake column for _search_func
   gtk_tree_view_set_search_equal_func(actions_view, _search_func, actions_view, NULL);
-  GtkWidget *search_actions = gtk_search_entry_new();
+  GtkSearchEntry *search_actions = GTK_SEARCH_ENTRY(gtk_search_entry_new());
   gtk_entry_set_placeholder_text(GTK_ENTRY(search_actions),
                                  _("search actions list"));
   gtk_widget_set_tooltip_text(GTK_WIDGET(search_actions),
                               _("incrementally search the list of actions\npress up or down keys to cycle through matches"));
-  g_signal_connect(G_OBJECT(search_actions), "activate",
+  g_signal_connect(search_actions, "activate",
                    G_CALLBACK(dt_gui_search_stop), actions_view);
-  g_signal_connect(G_OBJECT(search_actions), "stop-search",
+  g_signal_connect(search_actions, "stop-search",
                    G_CALLBACK(dt_gui_search_stop), actions_view);
   gtk_tree_view_set_search_entry(actions_view, GTK_ENTRY(search_actions));
 
   g_object_set(actions_view, "has-tooltip", TRUE, NULL);
   gtk_widget_set_name(GTK_WIDGET(actions_view), "actions_view");
-  g_signal_connect(G_OBJECT(actions_view), "row-activated",
+  g_signal_connect(actions_view, "row-activated",
                    G_CALLBACK(_action_row_activated), _actions_store);
-  g_signal_connect(G_OBJECT(actions_view), "button-press-event",
-                   G_CALLBACK(_action_view_click), _actions_store);
-  g_signal_connect(G_OBJECT(actions_view), "key-press-event",
+  g_signal_connect(actions_view, "button-press-event",
+                   G_CALLBACK(_action_view_click), NULL);
+  g_signal_connect(actions_view, "key-press-event",
                    G_CALLBACK(_view_key_pressed), search_actions);
 
-  g_signal_connect(G_OBJECT(gtk_tree_view_get_selection(actions_view)), "changed",
+  g_signal_connect(gtk_tree_view_get_selection(actions_view), "changed",
                    G_CALLBACK(_action_selection_changed), shortcuts_view);
-  g_signal_connect(G_OBJECT(gtk_tree_view_get_selection(shortcuts_view)), "changed",
+  g_signal_connect(gtk_tree_view_get_selection(shortcuts_view), "changed",
                    G_CALLBACK(_shortcut_selection_changed), actions_view);
 
   renderer = gtk_cell_renderer_text_new();
@@ -3053,7 +3047,7 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
 
   const int split_position = dt_conf_get_int("shortcuts/window_split");
   if(split_position) gtk_paned_set_position(GTK_PANED(container), split_position);
-  g_signal_connect(G_OBJECT(container), "notify::position",
+  g_signal_connect(container, "notify::position",
                    G_CALLBACK(_resize_shortcuts_view), container);
 
   GtkWidget *btn_fallbacks = gtk_check_button_new_with_label(_("enable fallbacks"));
@@ -3070,20 +3064,19 @@ GtkWidget *dt_shortcuts_prefs(GtkWidget *widget)
 
   GtkWidget *btn_restore = gtk_button_new_with_label(_("restore..."));
   gtk_widget_set_tooltip_text(btn_restore, _("restore default shortcuts or previous state"));
-  g_signal_connect(btn_restore, "clicked", G_CALLBACK(_restore_clicked), NULL);
+  g_signal_connect(GTK_BUTTON(btn_restore), "clicked", G_CALLBACK(_restore_clicked), NULL);
 
   GtkWidget *btn_importx = gtk_button_new_with_label(_("import extras"));
   gtk_widget_set_tooltip_text(btn_importx, _("import extended default shortcuts"));
-  g_signal_connect(btn_importx, "clicked", G_CALLBACK(_import_extended_clicked), NULL);
+  g_signal_connect(GTK_BUTTON(btn_importx), "clicked", G_CALLBACK(_import_extended_clicked), NULL);
 
   GtkWidget *btn_import = gtk_button_new_with_label(_("import..."));
   gtk_widget_set_tooltip_text(btn_import, _("fully or partially import shortcuts from file"));
-  g_signal_connect(btn_import, "clicked", G_CALLBACK(_import_clicked), NULL);
+  g_signal_connect(GTK_BUTTON(btn_import), "clicked", G_CALLBACK(_import_clicked), NULL);
 
   GtkWidget *btn_export = gtk_button_new_with_label(_("export..."));
   gtk_widget_set_tooltip_text(btn_export, _("fully or partially export shortcuts to file"));
-  g_signal_connect(btn_export, "clicked", G_CALLBACK(_export_clicked), NULL);
-
+  g_signal_connect(GTK_BUTTON(btn_export), "clicked", G_CALLBACK(_export_clicked), NULL);
   GtkWidget *button_bar = dt_gui_hbox(search_actions, search_shortcuts, btn_fallbacks,
                                       dt_gui_align_right(btn_help), btn_export, btn_importx,
                                       btn_import, btn_restore);
@@ -4910,7 +4903,7 @@ dt_action_t *dt_action_define(dt_action_t *owner,
       }
 
       gtk_widget_set_has_tooltip(widget, TRUE);
-      g_signal_connect(G_OBJECT(widget), "leave-notify-event",
+      g_signal_connect(widget, "leave-notify-event",
                        G_CALLBACK(_reset_element_on_leave), NULL);
     }
   }
@@ -5259,7 +5252,7 @@ GtkWidget *dt_action_button_new(dt_lib_module_t *self,
   gtk_label_set_ellipsize(GTK_LABEL(gtk_bin_get_child(GTK_BIN(button))),
                           PANGO_ELLIPSIZE_END);
   if(tooltip) gtk_widget_set_tooltip_text(button, tooltip);
-  g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(callback), data);
+  g_signal_connect(button, "clicked", G_CALLBACK((GtkCallback)callback), data);
 
   if(self)
   {
@@ -5285,7 +5278,7 @@ GtkWidget *dt_action_entry_new(dt_action_t *ac,
     gtk_entry_set_text (GTK_ENTRY(entry), text);
   if(tooltip)
     gtk_widget_set_tooltip_text(entry, tooltip);
-  g_signal_connect(G_OBJECT(entry), "changed", G_CALLBACK(callback), data);
+  g_signal_connect(entry, "changed", G_CALLBACK((GtkCallback)callback), data);
 
   dt_action_define(ac, NULL, label, entry, &dt_action_def_entry);
 
diff --git a/src/gui/color_picker_proxy.c b/src/gui/color_picker_proxy.c
index e131a8fed818..8a337c9842af 100644
--- a/src/gui/color_picker_proxy.c
+++ b/src/gui/color_picker_proxy.c
@@ -404,7 +404,7 @@ static GtkWidget *_color_picker_new(dt_iop_module_t *module,
       color_picker->picker_cst = cst;
       color_picker->fixed_cst = TRUE;
     }
-    g_signal_connect_data(G_OBJECT(button), "button-press-event",
+    g_signal_connect_data(button, "button-press-event",
                           G_CALLBACK(_color_picker_callback_button_press),
                           color_picker, (GClosureNotify)g_free, 0);
     if(w) gtk_box_pack_start(GTK_BOX(w), button, FALSE, FALSE, 0);
@@ -422,7 +422,7 @@ static GtkWidget *_color_picker_new(dt_iop_module_t *module,
       color_picker->picker_cst = cst;
       color_picker->fixed_cst = TRUE;
     }
-    g_signal_connect_data(G_OBJECT(w), "quad-pressed",
+    g_signal_connect_data(w, "quad-pressed",
                           G_CALLBACK(_color_picker_callback),
                           color_picker, (GClosureNotify)g_free, 0);
 
diff --git a/src/gui/gtk.c b/src/gui/gtk.c
index 228f9ad21f63..32fd7c7bbec0 100644
--- a/src/gui/gtk.c
+++ b/src/gui/gtk.c
@@ -752,10 +752,10 @@ static gboolean _borders_scrolled(GtkWidget *widget,
   return TRUE;
 }
 
-static gboolean _scrollbar_changed(GtkWidget *widget,
-                                   gpointer user_data)
+static void _scrollbar_changed(GtkWidget *widget,
+                               gpointer user_data)
 {
-  if(darktable.gui->reset) return FALSE;
+  if(darktable.gui->reset) return;
 
   GtkAdjustment *adjustment_x =
     gtk_range_get_adjustment(GTK_RANGE(darktable.gui->scrollbars.hscrollbar));
@@ -766,8 +766,6 @@ static gboolean _scrollbar_changed(GtkWidget *widget,
   const gdouble value_y = gtk_adjustment_get_value(adjustment_y);
 
   dt_view_manager_scrollbar_changed(darktable.view_manager, value_x, value_y);
-
-  return TRUE;
 }
 
 gboolean _valid_window_placement(const gint saved_x,
@@ -1190,7 +1188,7 @@ static void _osx_add_view_menu_item(GtkWidget* menu,
   GtkWidget *mi = gtk_menu_item_new_with_label(label);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
   gtk_widget_show(mi);
-  g_signal_connect(G_OBJECT(mi), "activate",
+  g_signal_connect(mi, "activate",
                    G_CALLBACK(_osx_ctl_switch_mode_to), mode);
 }
 
@@ -1342,13 +1340,13 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
   gtk_menu_shell_append(GTK_MENU_SHELL(help_menu), help_manual);
   gtk_widget_show(help_manual);
   dt_gui_add_help_link(help_manual, "document_root");
-  g_signal_connect(G_OBJECT(help_manual), "activate",
+  g_signal_connect(help_manual, "activate",
                    G_CALLBACK(dt_gui_show_help), help_manual);
 
   GtkWidget *help_home = gtk_menu_item_new_with_label(C_("menu", "darktable Homepage"));
   gtk_menu_shell_append(GTK_MENU_SHELL(help_menu), help_home);
   gtk_widget_show(help_home);
-  g_signal_connect(G_OBJECT(help_home), "activate",
+  g_signal_connect(help_home, "activate",
                    G_CALLBACK(_open_url), "https://www.darktable.org");
 
   gtk_menu_item_set_submenu(GTK_MENU_ITEM(help_root_menu), help_menu);
@@ -1366,21 +1364,21 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
   // GTK automatically translates the item with index 0 so no need to localize.
   // Furthermore, the application name (darktable) is automatically appended.
   GtkWidget *mi_about = gtk_menu_item_new_with_label("About");
-  g_signal_connect(G_OBJECT(mi_about), "activate",
+  g_signal_connect(mi_about, "activate",
                    G_CALLBACK(darktable_show_about_dialog), NULL);
   gtkosx_application_insert_app_menu_item(OSXApp, mi_about, 0);
 
   GtkWidget *mi_prefs = gtk_menu_item_new_with_label(C_("menu", "Preferences"));
-  g_signal_connect(G_OBJECT(mi_prefs), "activate",
+  g_signal_connect(mi_prefs, "activate",
                    G_CALLBACK(dt_gui_preferences_show), NULL);
   gtkosx_application_insert_app_menu_item(OSXApp, mi_prefs, 1);
 
   gtkosx_application_set_window_menu(OSXApp, GTK_MENU_ITEM(window_root_menu));
   gtkosx_application_set_help_menu(OSXApp, GTK_MENU_ITEM(help_root_menu));
 
-  g_signal_connect(G_OBJECT(OSXApp), "NSApplicationBlockTermination",
+  g_signal_connect(OSXApp, "NSApplicationBlockTermination",
                    G_CALLBACK(_osx_quit_callback), NULL);
-  g_signal_connect(G_OBJECT(OSXApp), "NSApplicationOpenFile",
+  g_signal_connect(OSXApp, "NSApplicationOpenFile",
                    G_CALLBACK(_osx_openfile_callback), NULL);
 #endif
 
@@ -1431,7 +1429,7 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
   _init_widgets(gui);
 
   widget = dt_ui_center(darktable.gui->ui);
-  g_signal_connect(G_OBJECT(widget), "configure-event",
+  g_signal_connect(widget, "configure-event",
                   G_CALLBACK(_configure), gui);
   for(int i = 2; i; i--, widget = dt_ui_snapshot(darktable.gui->ui))
   {
@@ -1440,19 +1438,19 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
                           | GDK_BUTTON_RELEASE_MASK | GDK_ENTER_NOTIFY_MASK
                           | GDK_LEAVE_NOTIFY_MASK | darktable.gui->scroll_mask);
 
-    g_signal_connect(G_OBJECT(widget), "draw",
+    g_signal_connect(widget, "draw",
                     G_CALLBACK(_draw), NULL);
-    g_signal_connect(G_OBJECT(widget), "motion-notify-event",
+    g_signal_connect(widget, "motion-notify-event",
                     G_CALLBACK(_mouse_moved), gui);
-    g_signal_connect(G_OBJECT(widget), "leave-notify-event",
+    g_signal_connect(widget, "leave-notify-event",
                     G_CALLBACK(_center_leave), NULL);
-    g_signal_connect(G_OBJECT(widget), "enter-notify-event",
+    g_signal_connect(widget, "enter-notify-event",
                     G_CALLBACK(_center_enter), NULL);
-    g_signal_connect(G_OBJECT(widget), "button-press-event",
+    g_signal_connect(widget, "button-press-event",
                     G_CALLBACK(_button_pressed), NULL);
-    g_signal_connect(G_OBJECT(widget), "button-release-event",
+    g_signal_connect(widget, "button-release-event",
                     G_CALLBACK(_button_released), NULL);
-    g_signal_connect(G_OBJECT(widget), "scroll-event",
+    g_signal_connect(widget, "scroll-event",
                     G_CALLBACK(_scrolled), NULL);
   }
 
@@ -1460,11 +1458,11 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
   // leave-notify-event
 
   widget = darktable.gui->scrollbars.vscrollbar;
-  g_signal_connect(G_OBJECT(widget), "value-changed",
+  g_signal_connect(widget, "value-changed",
                    G_CALLBACK(_scrollbar_changed), NULL);
 
   widget = darktable.gui->scrollbars.hscrollbar;
-  g_signal_connect(G_OBJECT(widget), "value-changed",
+  g_signal_connect(widget, "value-changed",
                    G_CALLBACK(_scrollbar_changed), NULL);
 
   dt_action_t *pnl = dt_action_section(&darktable.control->actions_global, N_("panels"));
@@ -1501,7 +1499,7 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
   */
   // update the profile when the window is moved. resize is already handled in configure()
   widget = dt_ui_main_window(darktable.gui->ui);
-  g_signal_connect(G_OBJECT(widget), "configure-event",
+  g_signal_connect(widget, "configure-event",
                    G_CALLBACK(_window_configure), NULL);
   g_signal_override_class_handler("query-tooltip", gtk_widget_get_type(),
                                   G_CALLBACK(dt_shortcut_tooltip_callback));
@@ -1590,7 +1588,7 @@ int dt_gui_gtk_init(dt_gui_gtk_t *gui)
     dtgtk_togglebutton_new(dtgtk_cairo_paint_focus_peaking, 0, NULL);
   gtk_widget_set_tooltip_text(darktable.gui->focus_peaking_button,
                               _("toggle focus-peaking mode"));
-  g_signal_connect(G_OBJECT(darktable.gui->focus_peaking_button), "clicked",
+  g_signal_connect(darktable.gui->focus_peaking_button, "clicked",
                    G_CALLBACK(_focuspeaking_switch_button_callback), NULL);
   _update_focus_peaking_button();
 
@@ -1689,27 +1687,19 @@ void dt_configure_ppd_dpi(dt_gui_gtk_t *gui)
 }
 
 static gboolean _focus_in_out_event(GtkWidget *widget,
-                                    GdkEvent *event,
-                                    const gpointer user_data)
+                                    GdkEventFocus *event,
+                                    GtkWidget *window)
 {
-  gtk_window_set_urgency_hint(GTK_WINDOW(user_data), FALSE);
+  gtk_window_set_urgency_hint(GTK_WINDOW(window), FALSE);
   return FALSE;
 }
 
 
 static gboolean _ui_log_button_press_event(GtkWidget *widget,
                                            GdkEvent *event,
-                                           const gpointer user_data)
-{
-  gtk_widget_hide(GTK_WIDGET(user_data));
-  return TRUE;
-}
-
-static gboolean _ui_toast_button_press_event(GtkWidget *widget,
-                                             GdkEvent *event,
-                                             const gpointer user_data)
+                                           GtkWidget *log)
 {
-  gtk_widget_hide(GTK_WIDGET(user_data));
+  gtk_widget_hide(log);
   return TRUE;
 }
 
@@ -1767,11 +1757,11 @@ static void _init_widgets(dt_gui_gtk_t *gui)
   gtk_window_set_icon_name(GTK_WINDOW(widget), "darktable");
   gtk_window_set_title(GTK_WINDOW(widget), "darktable");
 
-  g_signal_connect(G_OBJECT(widget), "delete_event",
+  g_signal_connect(widget, "delete-event",
                    G_CALLBACK(_gui_quit_callback), NULL);
-  g_signal_connect(G_OBJECT(widget), "focus-in-event",
+  g_signal_connect(widget, "focus-in-event",
                    G_CALLBACK(_focus_in_out_event), widget);
-  g_signal_connect(G_OBJECT(widget), "focus-out-event",
+  g_signal_connect(widget, "focus-out-event",
                    G_CALLBACK(_focus_in_out_event), widget);
 
   container = widget;
@@ -1866,7 +1856,7 @@ static void _init_main_table(GtkWidget *container)
   /* the log message */
   GtkWidget *eb = gtk_event_box_new();
   darktable.gui->ui->log_msg = gtk_label_new("");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_ui_log_button_press_event),
                    darktable.gui->ui->log_msg);
   gtk_label_set_ellipsize(GTK_LABEL(darktable.gui->ui->log_msg), PANGO_ELLIPSIZE_MIDDLE);
@@ -1880,11 +1870,11 @@ static void _init_main_table(GtkWidget *container)
   /* the toast message */
   eb = gtk_event_box_new();
   darktable.gui->ui->toast_msg = gtk_label_new("");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
-                   G_CALLBACK(_ui_toast_button_press_event),
+  g_signal_connect(eb, "button-press-event",
+                   G_CALLBACK(_ui_log_button_press_event),
                    darktable.gui->ui->toast_msg);
   gtk_widget_set_events(eb, GDK_BUTTON_PRESS_MASK | darktable.gui->scroll_mask);
-  g_signal_connect(G_OBJECT(eb), "scroll-event", G_CALLBACK(_scrolled), NULL);
+  g_signal_connect(eb, "scroll-event", G_CALLBACK(_scrolled), NULL);
   gtk_label_set_ellipsize(GTK_LABEL(darktable.gui->ui->toast_msg), PANGO_ELLIPSIZE_MIDDLE);
 
   PangoAttrList *attrlist = pango_attr_list_new();
@@ -2353,7 +2343,8 @@ static GtkWidget *_ui_init_panel_container_top(GtkWidget *container)
 }
 
 static gboolean _ui_init_panel_container_center_scroll_event(GtkWidget *widget,
-                                                             const GdkEventScroll *event)
+                                                             const GdkEventScroll *event,
+                                                             gpointer user_data)
 {
   // just make sure nothing happens unless ctrl-alt are pressed:
   return (((event->state & gtk_accelerator_get_default_mod_mask())
@@ -2361,7 +2352,7 @@ static gboolean _ui_init_panel_container_center_scroll_event(GtkWidget *widget,
           != dt_conf_get_bool("darkroom/ui/sidebar_scroll_default"));
 }
 
-static gboolean _on_drag_motion_drop(GtkWidget *empty, GdkDragContext *dc, const gint x, const gint y, const guint time, const gboolean drop)
+static gboolean _on_drag_motion_drop(GtkWidget *empty, GdkDragContext *dc, const gint x, const gint y, const guint time, gpointer drop)
 {
   GtkWidget *widget = gtk_widget_get_parent(empty);
   if(drop) gtk_widget_set_opacity(gtk_drag_get_source_widget(dc), 1.0);
@@ -2489,14 +2480,13 @@ static GtkWidget *_ui_init_panel_container_center(GtkWidget *container,
   gtk_scrolled_window_set_propagate_natural_width(GTK_SCROLLED_WINDOW(widget), TRUE);
 
   // we want the left/right window border to scroll the module lists
-  g_signal_connect(G_OBJECT(left
-                            ? darktable.gui->widgets.right_border
-                            : darktable.gui->widgets.left_border),
+  g_signal_connect(left ? darktable.gui->widgets.right_border
+                        : darktable.gui->widgets.left_border,
                    "scroll-event", G_CALLBACK(_borders_scrolled), widget);
 
   /* avoid scrolling with wheel, it's distracting (you'll end up over
    * a control, and scroll it's value) */
-  g_signal_connect(G_OBJECT(widget), "scroll-event",
+  g_signal_connect(widget, "scroll-event",
                    G_CALLBACK(_ui_init_panel_container_center_scroll_event),
                    NULL);
 
@@ -2532,7 +2522,7 @@ static GtkWidget *_ui_init_panel_container_bottom(GtkWidget *container)
 
 static gboolean _panel_handle_button_callback(GtkWidget *w,
                                               const GdkEventButton *e,
-                                              gpointer user_data)
+                                              GtkWidget *widget)
 {
   if(e->button == GDK_BUTTON_PRIMARY)
   {
@@ -2563,7 +2553,7 @@ static gboolean _panel_handle_button_callback(GtkWidget *w,
 }
 static gboolean _panel_handle_cursor_callback(GtkWidget *w,
                                               const GdkEventCrossing *e,
-                                              gpointer user_data)
+                                              GtkWidget *widget)
 {
   if(strcmp(gtk_widget_get_name(w), "panel-handle-bottom") == 0)
     dt_control_change_cursor((e->type == GDK_ENTER_NOTIFY)
@@ -2577,9 +2567,8 @@ static gboolean _panel_handle_cursor_callback(GtkWidget *w,
 }
 static gboolean _panel_handle_motion_callback(GtkWidget *w,
                                               const GdkEventMotion *e,
-                                              const gpointer user_data)
+                                              GtkWidget *widget)
 {
-  GtkWidget *widget = (GtkWidget *)user_data;
   if(darktable.gui->widgets.panel_handle_dragging)
   {
     gint sx = gtk_widget_get_allocated_width(widget);
@@ -2639,15 +2628,15 @@ static void _ui_init_panel_left(dt_ui_t *ui,
                         | GDK_LEAVE_NOTIFY_MASK | GDK_POINTER_MOTION_MASK);
   gtk_widget_set_name(GTK_WIDGET(handle), "panel-handle-left");
 
-  g_signal_connect(G_OBJECT(handle), "button-press-event",
+  g_signal_connect(handle, "button-press-event",
                    G_CALLBACK(_panel_handle_button_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "button-release-event",
+  g_signal_connect(handle, "button-release-event",
                    G_CALLBACK(_panel_handle_button_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "motion-notify-event",
+  g_signal_connect(handle, "motion-notify-event",
                    G_CALLBACK(_panel_handle_motion_callback), widget);
-  g_signal_connect(G_OBJECT(handle), "leave-notify-event",
+  g_signal_connect(handle, "leave-notify-event",
                    G_CALLBACK(_panel_handle_cursor_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "enter-notify-event",
+  g_signal_connect(handle, "enter-notify-event",
                    G_CALLBACK(_panel_handle_cursor_callback), handle);
   gtk_widget_show(handle);
 
@@ -2689,15 +2678,15 @@ static void _ui_init_panel_right(dt_ui_t *ui,
                         | GDK_ENTER_NOTIFY_MASK
                         | GDK_LEAVE_NOTIFY_MASK | GDK_POINTER_MOTION_MASK);
   gtk_widget_set_name(GTK_WIDGET(handle), "panel-handle-right");
-  g_signal_connect(G_OBJECT(handle), "button-press-event",
+  g_signal_connect(handle, "button-press-event",
                    G_CALLBACK(_panel_handle_button_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "button-release-event",
+  g_signal_connect(handle, "button-release-event",
                    G_CALLBACK(_panel_handle_button_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "motion-notify-event",
+  g_signal_connect(handle, "motion-notify-event",
                    G_CALLBACK(_panel_handle_motion_callback), widget);
-  g_signal_connect(G_OBJECT(handle), "leave-notify-event",
+  g_signal_connect(handle, "leave-notify-event",
                    G_CALLBACK(_panel_handle_cursor_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "enter-notify-event",
+  g_signal_connect(handle, "enter-notify-event",
                    G_CALLBACK(_panel_handle_cursor_callback), handle);
   gtk_widget_show(handle);
 
@@ -2776,15 +2765,15 @@ static void _ui_init_panel_bottom(dt_ui_t *ui,
                         | GDK_LEAVE_NOTIFY_MASK | GDK_POINTER_MOTION_MASK);
   gtk_widget_set_name(GTK_WIDGET(handle), "panel-handle-bottom");
 
-  g_signal_connect(G_OBJECT(handle), "button-press-event",
+  g_signal_connect(handle, "button-press-event",
                    G_CALLBACK(_panel_handle_button_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "button-release-event",
+  g_signal_connect(handle, "button-release-event",
                    G_CALLBACK(_panel_handle_button_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "motion-notify-event",
+  g_signal_connect(handle, "motion-notify-event",
                    G_CALLBACK(_panel_handle_motion_callback), widget);
-  g_signal_connect(G_OBJECT(handle), "leave-notify-event",
+  g_signal_connect(handle, "leave-notify-event",
                    G_CALLBACK(_panel_handle_cursor_callback), handle);
-  g_signal_connect(G_OBJECT(handle), "enter-notify-event",
+  g_signal_connect(handle, "enter-notify-event",
                    G_CALLBACK(_panel_handle_cursor_callback), handle);
   gtk_widget_show(handle);
 
@@ -3061,7 +3050,7 @@ gboolean dt_gui_show_standalone_yes_no_dialog(const char *title,
   {
     button = gtk_button_new_with_mnemonic(no_text);
     result.button_no = button;
-    g_signal_connect(G_OBJECT(button), "clicked",
+    g_signal_connect(button, "clicked",
                      G_CALLBACK(_yes_no_button_handler), &result);
     gtk_box_pack_start(GTK_BOX(hbox), button, TRUE, TRUE, 0);
   }
@@ -3070,7 +3059,7 @@ gboolean dt_gui_show_standalone_yes_no_dialog(const char *title,
   {
     button = gtk_button_new_with_mnemonic(yes_text);
     result.button_yes = button;
-    g_signal_connect(G_OBJECT(button), "clicked",
+    g_signal_connect(button, "clicked",
                      G_CALLBACK(_yes_no_button_handler), &result);
     gtk_box_pack_start(GTK_BOX(hbox), button, TRUE, TRUE, 0);
   }
@@ -3148,7 +3137,7 @@ char *dt_gui_show_standalone_string_dialog(const char *title,
   {
     button = gtk_button_new_with_label(no_text);
     result.button_no = button;
-    g_signal_connect(G_OBJECT(button), "clicked",
+    g_signal_connect(button, "clicked",
                      G_CALLBACK(_yes_no_button_handler), &result);
     gtk_box_pack_start(GTK_BOX(hbox), button, TRUE, TRUE, 0);
   }
@@ -3157,7 +3146,7 @@ char *dt_gui_show_standalone_string_dialog(const char *title,
   {
     button = gtk_button_new_with_label(yes_text);
     result.button_yes = button;
-    g_signal_connect(G_OBJECT(button), "clicked",
+    g_signal_connect(button, "clicked",
                      G_CALLBACK(_yes_no_button_handler), &result);
     gtk_box_pack_start(GTK_BOX(hbox), button, TRUE, TRUE, 0);
   }
@@ -3274,7 +3263,7 @@ static char *_get_base_url()
     return base_url;
 }
 
-void dt_gui_show_help(GtkWidget *widget)
+void dt_gui_show_help(GtkWidget *widget, gpointer user_data)
 {
   // TODO: When the widget doesn't have a help url set we should
   // probably look at the parent(s)
@@ -3603,7 +3592,7 @@ static void _reset_all_bauhaus(GtkNotebook *notebook,
 
 static void _notebook_size_callback(GtkNotebook *notebook,
                                     GdkRectangle *allocation,
-                                    gpointer *data)
+                                    gpointer data)
 {
   const int n = gtk_notebook_get_n_pages(notebook);
   g_return_if_fail(n > 0);
@@ -3820,13 +3809,13 @@ GtkWidget *dt_ui_notebook_page(GtkNotebook *notebook,
      !g_signal_handler_find(G_OBJECT(notebook),
                             G_SIGNAL_MATCH_FUNC, 0, 0, NULL, _notebook_size_callback, NULL))
   {
-    g_signal_connect(G_OBJECT(notebook), "size-allocate",
+    g_signal_connect(notebook, "size-allocate",
                      G_CALLBACK(_notebook_size_callback), NULL);
-    g_signal_connect(G_OBJECT(notebook), "motion-notify-event",
+    g_signal_connect(notebook, "motion-notify-event",
                      G_CALLBACK(_notebook_motion_notify_callback), NULL);
-    g_signal_connect(G_OBJECT(notebook), "scroll-event",
+    g_signal_connect(notebook, "scroll-event",
                      G_CALLBACK(_notebook_scroll_callback), NULL);
-    g_signal_connect(G_OBJECT(notebook), "button-press-event",
+    g_signal_connect(notebook, "button-press-event",
                      G_CALLBACK(_notebook_button_press_callback), NULL);
     gtk_widget_add_events(GTK_WIDGET(notebook), darktable.gui->scroll_mask);
   }
@@ -3915,8 +3904,8 @@ static gint _get_container_row_heigth(GtkWidget *w)
 }
 
 static gboolean _resize_wrap_draw(GtkWidget *w,
-                                  void *cr,
-                                  const char *config_str)
+                                  cairo_t *cr,
+                                  char *config_str)
 {
   GtkWidget *sw = gtk_widget_get_parent(w);
   if(GTK_IS_VIEWPORT(sw)) sw = gtk_widget_get_parent(sw);
@@ -3972,7 +3961,7 @@ static gboolean _resize_wrap_draw(GtkWidget *w,
 
 static gboolean _resize_wrap_scroll(GtkScrolledWindow *sw,
                                     GdkEventScroll *event,
-                                    const char *config_str)
+                                    char *config_str)
 {
   // no move needed
   int delta_y = 0;
@@ -4018,7 +4007,7 @@ static gboolean _resize_wrap_scroll(GtkScrolledWindow *sw,
 
 static gboolean _scroll_wrap_height(GtkWidget *w,
                                     const GdkEventScroll *event,
-                                    const char *config_str)
+                                    char *config_str)
 {
   if(dt_modifier_is(event->state, GDK_SHIFT_MASK | GDK_MOD1_MASK))
   {
@@ -4062,7 +4051,7 @@ static gboolean _resize_wrap_draw_handle(GtkWidget *w,
 
 static gboolean _resize_wrap_motion(GtkWidget *widget,
                                     const GdkEventMotion *event,
-                                    const char *config_str)
+                                    char *config_str)
 {
   if(_resize_wrap_dragging)
   {
@@ -4094,7 +4083,7 @@ static gboolean _resize_wrap_motion(GtkWidget *widget,
 
 static gboolean _resize_wrap_button(GtkWidget *widget,
                                     const GdkEventButton *event,
-                                    const char *config_str)
+                                    char *config_str)
 {
   if(_resize_wrap_dragging
      && event->type == GDK_BUTTON_RELEASE)
@@ -4113,10 +4102,9 @@ static gboolean _resize_wrap_button(GtkWidget *widget,
 
   return FALSE;
 }
-
 static gboolean _resize_wrap_enter_leave(GtkWidget *widget,
                                          const GdkEventCrossing *event,
-                                         const char *config_str)
+                                         char *config_str)
 {
   _resize_wrap_hovered =
     event->type == GDK_ENTER_NOTIFY
@@ -4147,10 +4135,9 @@ GtkWidget *dt_ui_resize_wrap(GtkWidget *w,
   {
     const float height = dt_conf_get_int(config_str);
     dtgtk_drawing_area_set_height(w, height);
-    g_signal_connect(G_OBJECT(w),
-                              "scroll-event",
-                              G_CALLBACK(_scroll_wrap_height),
-                              config_str);
+    g_signal_connect(w, "scroll-event",
+                     G_CALLBACK(_scroll_wrap_height),
+                     config_str);
   }
   else
   {
@@ -4159,9 +4146,9 @@ GtkWidget *dt_ui_resize_wrap(GtkWidget *w,
                                    GTK_POLICY_NEVER, GTK_POLICY_AUTOMATIC);
     gtk_scrolled_window_set_min_content_height
       (GTK_SCROLLED_WINDOW(sw), - DT_PIXEL_APPLY_DPI(min_size));
-    g_signal_connect(G_OBJECT(sw), "scroll-event",
+    g_signal_connect(GTK_SCROLLED_WINDOW(sw), "scroll-event",
                      G_CALLBACK(_resize_wrap_scroll), config_str);
-    g_signal_connect(G_OBJECT(w), "draw",
+    g_signal_connect(w, "draw",
                      G_CALLBACK(_resize_wrap_draw), config_str);
     gtk_widget_set_margin_bottom(sw, DT_RESIZE_HANDLE_SIZE);
     w = gtk_event_box_new();
@@ -4171,17 +4158,17 @@ GtkWidget *dt_ui_resize_wrap(GtkWidget *w,
   gtk_widget_add_events(w, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                          | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK
                          | GDK_POINTER_MOTION_MASK | darktable.gui->scroll_mask);
-  g_signal_connect(G_OBJECT(w), "motion-notify-event",
+  g_signal_connect(w, "motion-notify-event",
                    G_CALLBACK(_resize_wrap_motion), config_str);
-  g_signal_connect(G_OBJECT(w), "button-press-event",
+  g_signal_connect(w, "button-press-event",
                    G_CALLBACK(_resize_wrap_button), config_str);
-  g_signal_connect(G_OBJECT(w), "button-release-event",
+  g_signal_connect(w, "button-release-event",
                    G_CALLBACK(_resize_wrap_button), config_str);
-  g_signal_connect(G_OBJECT(w), "enter-notify-event",
+  g_signal_connect(w, "enter-notify-event",
                    G_CALLBACK(_resize_wrap_enter_leave), config_str);
-  g_signal_connect(G_OBJECT(w), "leave-notify-event",
+  g_signal_connect(w, "leave-notify-event",
                    G_CALLBACK(_resize_wrap_enter_leave), config_str);
-  g_signal_connect_after(G_OBJECT(w), "draw",
+  g_signal_connect_after(w, "draw",
                          G_CALLBACK(_resize_wrap_draw_handle), NULL);
 
   return w;
@@ -4256,7 +4243,7 @@ void dt_gui_menu_popup(GtkMenu *menu,
 {
   gtk_widget_show_all(GTK_WIDGET(menu));
   g_object_ref_sink(G_OBJECT(menu));
-  g_signal_connect(G_OBJECT(menu), "deactivate", G_CALLBACK(g_object_unref), NULL);
+  g_signal_connect(menu, "deactivate", G_CALLBACK(g_object_unref), NULL);
 
   GdkEvent *event = gtk_get_current_event();
   if(button && event)
@@ -4310,7 +4297,7 @@ gboolean dt_gui_search_start(GtkWidget *widget,
                              GdkEventKey *event,
                              GtkSearchEntry *entry)
 {
-  if(gtk_search_entry_handle_event(entry, (GdkEvent *)event))
+  if(gtk_search_entry_handle_event(GTK_SEARCH_ENTRY(entry), (GdkEvent *)event))
   {
     gtk_entry_grab_focus_without_selecting(GTK_ENTRY(entry));
     return TRUE;
@@ -4320,27 +4307,25 @@ gboolean dt_gui_search_start(GtkWidget *widget,
 }
 
 void dt_gui_search_stop(GtkSearchEntry *entry,
-                        GtkWidget *widget)
+                        GtkTreeView *widget)
 {
-  gtk_widget_grab_focus(widget);
+  gtk_widget_grab_focus(GTK_WIDGET(widget));
 
   gtk_entry_set_text(GTK_ENTRY(entry), "");
 
-  if(GTK_IS_TREE_VIEW(widget))
+  if(widget)
   {
     GtkTreePath *path = NULL;
-    gtk_tree_view_get_cursor(GTK_TREE_VIEW(widget), &path, NULL);
+    gtk_tree_view_get_cursor(widget, &path, NULL);
     gtk_tree_selection_select_path
-      (gtk_tree_view_get_selection(GTK_TREE_VIEW(widget)), path);
+      (gtk_tree_view_get_selection(widget), path);
     gtk_tree_path_free(path);
   }
 }
 
-static void _collapse_button_changed(GtkDarktableToggleButton *widget,
-                                     const gpointer user_data)
+static void _collapse_button_changed(GtkWidget *widget,
+                                     dt_gui_collapsible_section_t *cs)
 {
-  const dt_gui_collapsible_section_t *cs = (dt_gui_collapsible_section_t *)user_data;
-
   if(cs->module && cs->module->type == DT_ACTION_TYPE_IOP_INSTANCE)
       dt_iop_request_focus((dt_iop_module_t *)cs->module);
   else if(cs->module && cs->module->type == DT_ACTION_TYPE_LIB)
@@ -4356,12 +4341,10 @@ static void _collapse_button_changed(GtkDarktableToggleButton *widget,
 
 static gboolean _collapse_expander_click(GtkWidget *widget,
                                          const GdkEventButton *e,
-                                         const gpointer user_data)
+                                         dt_gui_collapsible_section_t *cs)
 {
   if(e->button != 1) return FALSE;
 
-  const dt_gui_collapsible_section_t *cs = (dt_gui_collapsible_section_t *)user_data;
-
   const gboolean active = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(cs->toggle));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(cs->toggle), !active);
 
@@ -4424,10 +4407,10 @@ void dt_gui_new_collapsible_section(dt_gui_collapsible_section_t *cs,
   dtgtk_expander_set_expanded(DTGTK_EXPANDER(cs->expander), expanded);
   gtk_widget_set_name(cs->expander, "collapse-block");
 
-  g_signal_connect(G_OBJECT(cs->toggle), "toggled",
+  g_signal_connect(cs->toggle, "toggled",
                    G_CALLBACK(_collapse_button_changed), cs);
 
-  g_signal_connect(G_OBJECT(header_evb), "button-press-event",
+  g_signal_connect(header_evb, "button-press-event",
                    G_CALLBACK(_collapse_expander_click), cs);
 }
 
@@ -4448,9 +4431,9 @@ gboolean dt_gui_long_click(const guint second,
   return second - delay > first;
 }
 
-static void _gesture_cancel(GtkGestureSingle *gesture,
+static void _gesture_cancel(GtkGesture *gesture,
                             GdkEventSequence *sequence,
-                            GtkWidget *widget)
+                            gpointer user_data)
 {
   g_signal_emit_by_name(gesture, "released", 1, .0, .0);
 }
@@ -4461,14 +4444,14 @@ GtkGestureSingle *(dt_gui_connect_click)(GtkWidget *widget,
                                          gpointer data)
 {
   GtkGesture *gesture = gtk_gesture_multi_press_new(widget);
-  g_object_weak_ref(G_OBJECT (widget), (GWeakNotify) g_object_unref, gesture);
+  g_object_weak_ref(G_OBJECT(widget), (GWeakNotify) g_object_unref, gesture);
   // GTK4 GtkGesture *gesture = gtk_gesture_click_new();
   //      gtk_widget_add_controller(widget, GTK_EVENT_CONTROLLER(gesture));
 
-  if(pressed) g_signal_connect(gesture, "pressed", pressed, data);
+  if(pressed) g_signal_connect(gesture, "pressed", G_CALLBACK(pressed), data);
   if(released)
   {
-    g_signal_connect(gesture, "released", released, data);
+    g_signal_connect(gesture, "released", G_CALLBACK(released), data);
     g_signal_connect(gesture, "cancel", G_CALLBACK(_gesture_cancel), NULL);
   }
 
@@ -4488,9 +4471,9 @@ GtkEventController *(dt_gui_connect_motion)(GtkWidget *widget,
 
   gtk_widget_add_events(widget, GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK); // still needed for now by _main_do_event_keymap
 
-  if(motion) g_signal_connect(controller, "motion", motion, data);
-  if(enter) g_signal_connect(controller, "enter", enter, data);
-  if(leave) g_signal_connect(controller, "leave", leave, data);
+  if(motion) g_signal_connect(controller, "motion", G_CALLBACK(motion), data);
+  if(enter) g_signal_connect(controller, "enter", G_CALLBACK(enter), data);
+  if(leave) g_signal_connect(controller, "leave", G_CALLBACK(leave), data);
 
   return controller;
 }
diff --git a/src/gui/gtk.h b/src/gui/gtk.h
index 8ee46777e981..c5d09a960597 100644
--- a/src/gui/gtk.h
+++ b/src/gui/gtk.h
@@ -460,7 +460,7 @@ void dt_gui_add_help_link(GtkWidget *widget,
 char *dt_gui_get_help_url(GtkWidget *widget);
 void dt_gui_dialog_add_help(GtkDialog *dialog,
                             const char *topic);
-void dt_gui_show_help(GtkWidget *widget);
+void dt_gui_show_help(GtkWidget *widget, gpointer user_data);
 
 // load a CSS theme
 void dt_gui_load_theme(const char *theme); // read them and add user tweaks
@@ -521,7 +521,7 @@ gboolean dt_gui_search_start(GtkWidget *widget,
 
 // event handler for "stop-search" of GtkSearchEntry
 void dt_gui_search_stop(GtkSearchEntry *entry,
-                        GtkWidget *widget);
+                        GtkTreeView *widget);
 
 // create a collapsible section, insert in parent, return the container
 void dt_gui_new_collapsible_section(dt_gui_collapsible_section_t *cs,
@@ -569,6 +569,154 @@ GtkEventController *(dt_gui_connect_motion)(GtkWidget *widget,
   ASSERT_FUNC_TYPE(leave, void(*)(GtkEventControllerMotion *, __typeof__(data))), \
   dt_gui_connect_motion(GTK_WIDGET(widget), G_CALLBACK(motion), G_CALLBACK(enter), G_CALLBACK(leave), (data)))
 
+// Enable compile-time checking of signal handler signatures
+// Uncomment the _Static_assert to stop compilation on mismatch
+// Otherwise errors will be printed at runtime, but only when the signal is connected
+// (so all dialogs, menus etc must be opened to see all errors)
+// No code is generated when the test is passed
+#if 1 && !defined(__cplusplus)
+#undef G_CALLBACK
+static inline GCallback G_CALLBACK(void *f) { return (GCallback)f; } // as a macro it gets expanded before reaching here
+#define DISABLINGPREFIXG_CALLBACK
+
+#define SIGNAME(num, signal, name) !strcmp((signal), #name) ? 1 << num :
+#define RETURN_HANDLER(num, ret, instance, data, ...) ret(*)(instance, __VA_OPT__(__VA_ARGS__,) data) : 1 << num,
+#define BOOL_HANDLER(num, instance, data, ...) RETURN_HANDLER(num, gboolean, instance, data, __VA_ARGS__)
+#define VOID_HANDLER(num, instance, data, ...) RETURN_HANDLER(num, void, instance, data, __VA_ARGS__)
+#define EVENT_HANDLER(num, instance, data, event) BOOL_HANDLER(num, instance, data, GdkEvent##event*) \
+                                                  BOOL_HANDLER(num, instance, data, const GdkEvent##event*)
+#define MATCH_HANDLER(c_handler, instance, data) \
+  _Generic((DISABLINGPREFIX##c_handler), \
+    GCallback : 1 << 0, \
+    EVENT_HANDLER(1, instance, data, ) \
+    EVENT_HANDLER(1, instance, data, Button) \
+    EVENT_HANDLER(1, instance, data, Motion) \
+    EVENT_HANDLER(1, instance, data, Scroll) \
+    EVENT_HANDLER(1, instance, data, Key) \
+    EVENT_HANDLER(1, instance, data, Focus) \
+    EVENT_HANDLER(1, instance, data, Crossing) \
+    EVENT_HANDLER(1, instance, data, Configure) \
+    VOID_HANDLER( 2, instance, data) \
+    VOID_HANDLER( 3, instance, data, char*, GtkTreeIter*) \
+    VOID_HANDLER( 4, instance, data, GdkRectangle*, GdkRectangle*, gboolean, gboolean) \
+    VOID_HANDLER( 5, instance, data, char*) \
+    BOOL_HANDLER( 6, instance, data, gint, gint, gboolean, GtkTooltip*) \
+    BOOL_HANDLER( 7, instance, data, cairo_t*) \
+    VOID_HANDLER( 8, instance, data, GtkWidget*) \
+    VOID_HANDLER( 8, instance, data, GdkRectangle*) \
+    VOID_HANDLER( 8, instance, data, GdkEventSequence*) \
+    VOID_HANDLER( 8, instance, data, GdkDragContext*) \
+    VOID_HANDLER( 9, instance, data, GdkDragContext*, guint) \
+    VOID_HANDLER( 9, instance, data, GtkWidget*, guint) \
+    BOOL_HANDLER(10, instance, data, GdkDragContext*, const gint, const gint, const guint) \
+    VOID_HANDLER(11, instance, data, GtkTreePath*, GtkTreeViewColumn*) \
+    VOID_HANDLER(12, instance, data, gint) \
+    VOID_HANDLER(13, instance, data, GdkDragContext*, gint, gint, GtkSelectionData*, guint, guint) \
+    VOID_HANDLER(14, instance, data, GdkDragContext*, GtkSelectionData*, guint, guint) \
+    BOOL_HANDLER(15, instance, data, GdkDragContext*, GtkDragResult) \
+    VOID_HANDLER(16, instance, data, GtkCellEditable*, char*) \
+    VOID_HANDLER(17, instance, data, const gchar*, const gchar*) \
+    BOOL_HANDLER(18, instance, data, GtkDirectionType) \
+    BOOL_HANDLER(19, instance, data) \
+    VOID_HANDLER(20, instance, data, const gchar*, const gint, gint*) \
+    VOID_HANDLER(21, instance, data, GtkTreePath*, GtkTreeIter*) \
+    VOID_HANDLER(22, instance, data, GParamSpec*) \
+    VOID_HANDLER(23, instance, data, GtkTreeIter*, GtkTreePath*) \
+    BOOL_HANDLER(24, instance, data, GtkTreeModel*, GtkTreeIter*) \
+    default : 0)
+#define MATCH_HANDLER_BOTH(c_handler, instance, data) MATCH_HANDLER(c_handler, instance, data) ?: \
+                                                      MATCH_HANDLER(c_handler, instance, gpointer)
+#undef _Static_assert
+#undef  g_signal_connect
+#define g_signal_connect(instance, signal, c_handler, user_data) do { \
+  const int required_signature = \
+    SIGNAME( 0, signal, pressed) \
+    SIGNAME( 0, signal, released) \
+    SIGNAME( 0, signal, motion) \
+    SIGNAME( 0, signal, enter) \
+    SIGNAME( 0, signal, leave) \
+    SIGNAME( 1, signal, event) \
+    SIGNAME( 1, signal, button-press-event) \
+    SIGNAME( 1, signal, button-release-event) \
+    SIGNAME( 1, signal, motion-notify-event) \
+    SIGNAME( 1, signal, scroll-event) \
+    SIGNAME( 1, signal, enter-notify-event) \
+    SIGNAME( 1, signal, leave-notify-event) \
+    SIGNAME( 1, signal, key-press-event) \
+    SIGNAME( 1, signal, focus-out-event) \
+    SIGNAME( 1, signal, focus-in-event) \
+    SIGNAME( 1, signal, delete-event) \
+    SIGNAME( 1, signal, configure-event) \
+    SIGNAME( 1 | 1 << 2 | 1 << 3 , signal, changed) \
+    SIGNAME( 2 | 1 << 5, signal, toggled) \
+    SIGNAME( 2, signal, clicked) \
+    SIGNAME( 2, signal, value-changed) \
+    SIGNAME( 2, signal, value-reset) \
+    SIGNAME( 2, signal, quad-pressed) \
+    SIGNAME( 2, signal, show) \
+    SIGNAME( 2, signal, closed) \
+    SIGNAME( 2, signal, stopped) \
+    SIGNAME( 2, signal, stop-search) \
+    SIGNAME( 2, signal, day_selected) \
+    SIGNAME( 2, signal, day_selected-double-click) \
+    SIGNAME( 2, signal, selection-changed) \
+    SIGNAME( 2, signal, activate) \
+    SIGNAME( 2, signal, deactivate) \
+    SIGNAME( 2, signal, editing-done) \
+    SIGNAME( 2, signal, style-updated) \
+    SIGNAME( 2, signal, search-changed) \
+    SIGNAME( 2, signal, mounts-changed) \
+    SIGNAME( 2, signal, color-set) \
+    SIGNAME( 2, signal, font-set) \
+    SIGNAME( 2, signal, destroy) \
+    SIGNAME( 4, signal, moved-to-rect) \
+    SIGNAME( 6, signal, query-tooltip) \
+    SIGNAME( 7, signal, draw) \
+    SIGNAME( 8, signal, add) \
+    SIGNAME( 8, signal, remove) \
+    SIGNAME( 8, signal, cancel) \
+    SIGNAME( 8, signal, size-allocate) \
+    SIGNAME( 8, signal, populate-popup) \
+    SIGNAME( 8, signal, drag-begin) \
+    SIGNAME( 8, signal, drag-end) \
+    SIGNAME( 9, signal, drag-leave) \
+    SIGNAME( 9, signal, switch-page) \
+    SIGNAME(10, signal, drag-motion) \
+    SIGNAME(10, signal, drag-drop) \
+    SIGNAME(11, signal, row-activated) \
+    SIGNAME(12, signal, response) \
+    SIGNAME(13, signal, drag-data-received) \
+    SIGNAME(14, signal, drag-data-get) \
+    SIGNAME(15, signal, drag-failed) \
+    SIGNAME(16, signal, editing-started) \
+    SIGNAME(17, signal, edited) \
+    SIGNAME(18, signal, focus) \
+    SIGNAME(19, signal, popup-menu) \
+    SIGNAME(20, signal, insert-text) \
+    SIGNAME(21, signal, row-inserted) \
+    SIGNAME(22, signal, notify::position) \
+    SIGNAME(22, signal, notify::visible) \
+    SIGNAME(23, signal, row-expanded) \
+    SIGNAME(24, signal, match-selected) \
+    0; \
+  const int found_signature = MATCH_HANDLER_BOTH(c_handler, __typeof__(instance), __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkWidget*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkEntry*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkDrawingArea*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkTreeView*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkTextView*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkColorButton*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkToggleButton*, __typeof__(user_data)) ?: \
+                              MATCH_HANDLER_BOTH(c_handler, GtkButton*, __typeof__(user_data)); \
+  if(required_signature == 0) \
+    dt_print_nts_ext("%s:%d: connecting unknown signal %s\n", __FILE__, __LINE__, signal); \
+  else if(!(required_signature & found_signature)) \
+    dt_print_nts_ext("%s:%d: connecting signal %s to %s with incorrect signature %d-%d\n", __FILE__, __LINE__, signal, #c_handler, required_signature, found_signature); \
+  /*_Static_assert(required_signature, "unknown signal encountered: " signal ); */\
+  /*_Static_assert(required_signature & found_signature, "incorrect function connected to " signal ); */\
+  g_signal_connect_data ((instance), (signal), (c_handler), (user_data), NULL, (GConnectFlags) 0); } while(0)
+#endif // __cplusplus
+
 // GTK4 gtk_event_controller_get_current_event_state(GTK_EVENT_CONTROLLER(controller));
 #define dt_modifier_eq(controller, mask)\
   dt_modifier_is(dt_key_modifier_state(), mask)
diff --git a/src/gui/gtkentry.c b/src/gui/gtkentry.c
index e02007626364..d738189c2b00 100644
--- a/src/gui/gtkentry.c
+++ b/src/gui/gtkentry.c
@@ -279,7 +279,7 @@ void dt_gtkentry_setup_variables_completion(GtkEntry *entry)
   GtkEntryCompletion *completion = gtk_entry_completion_new();
   gtk_entry_completion_set_text_column(completion, COMPL_DESCRIPTION);
   gtk_entry_set_completion(entry, completion);
-  g_signal_connect(G_OBJECT(completion), "match-selected", G_CALLBACK(_on_match_select), NULL);
+  g_signal_connect(completion, "match-selected", G_CALLBACK(_on_match_select), NULL);
 
   gtk_entry_completion_set_model(completion, GTK_TREE_MODEL(_completion_model));
   gtk_entry_completion_set_match_func(completion, _on_match_func, NULL, NULL);
diff --git a/src/gui/guides.c b/src/gui/guides.c
index f0060e522370..8f335c2f5768 100644
--- a/src/gui/guides.c
+++ b/src/gui/guides.c
@@ -236,7 +236,7 @@ static GtkWidget *_guides_gui_grid(dt_iop_module_t *self,
   dt_bauhaus_slider_set(grid_horizontal,
                         dt_conf_key_exists(key) ? dt_conf_get_int(key) : 3);
   g_free(key);
-  g_signal_connect(G_OBJECT(grid_horizontal), "value-changed",
+  g_signal_connect(grid_horizontal, "value-changed",
                    G_CALLBACK(_grid_horizontal_changed), user_data);
 
   GtkWidget *grid_vertical = dt_bauhaus_slider_new_with_range(NULL, 0, 12, 1, 3, 0);
@@ -246,7 +246,7 @@ static GtkWidget *_guides_gui_grid(dt_iop_module_t *self,
   key = _conf_get_path("global", "grid_nbv", NULL);
   dt_bauhaus_slider_set(grid_vertical, dt_conf_key_exists(key) ? dt_conf_get_int(key) : 3);
   g_free(key);
-  g_signal_connect(G_OBJECT(grid_vertical), "value-changed",
+  g_signal_connect(grid_vertical, "value-changed",
                    G_CALLBACK(_grid_vertical_changed), user_data);
 
   GtkWidget *grid_subdiv = dt_bauhaus_slider_new_with_range(NULL, 0, 10, 1, 3, 0);
@@ -256,7 +256,7 @@ static GtkWidget *_guides_gui_grid(dt_iop_module_t *self,
   key = _conf_get_path("global", "grid_subdiv", NULL);
   dt_bauhaus_slider_set(grid_subdiv, dt_conf_key_exists(key) ? dt_conf_get_int(key) : 3);
   g_free(key);
-  g_signal_connect(G_OBJECT(grid_subdiv), "value-changed",
+  g_signal_connect(grid_subdiv, "value-changed",
                    G_CALLBACK(_grid_subdiv_changed), user_data);
 
   return dt_gui_vbox(grid_horizontal, grid_vertical, grid_subdiv);
@@ -802,7 +802,7 @@ static void _settings_colors_changed(GtkWidget *combo,
 }
 
 static void _settings_contrast_changed(GtkWidget *slider,
-                                       _guides_settings_t *gw)
+                                       gpointer user_data)
 {
   dt_conf_set_float("darkroom/ui/overlay_contrast", dt_bauhaus_slider_get(slider));
   dt_guides_set_overlay_colors();
@@ -865,7 +865,7 @@ GtkWidget *dt_guides_popover(dt_view_t *self,
      _("set the contrast between the lightest and darkest part of the guide overlays"));
   dt_bauhaus_slider_set(contrast,
                         dt_conf_get_float("darkroom/ui/overlay_contrast"));
-  g_signal_connect(G_OBJECT(contrast), "value-changed",
+  g_signal_connect(contrast, "value-changed",
                    G_CALLBACK(_settings_contrast_changed), NULL);
 
   GtkWidget *vbox = dt_gui_vbox(lb, gw->g_widgets, gw->g_flip, darktable.view_manager->guides,
@@ -984,7 +984,7 @@ void dt_guides_add_module_menuitem(void *menu,
   gchar *key = _conf_get_path(module->op, "autoshow", NULL);
   gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(mi), dt_conf_get_bool(key));
   g_free(key);
-  g_signal_connect(G_OBJECT(mi), "activate",
+  g_signal_connect(mi, "activate",
                    G_CALLBACK(_settings_autoshow_change), module);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
@@ -1036,14 +1036,14 @@ void dt_guides_init_module_widget(GtkWidget *iopw,
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(cb), dt_conf_get_bool(key));
   g_free(key);
 
-  g_signal_connect(G_OBJECT(cb), "toggled",
+  g_signal_connect(cb, "toggled",
                    G_CALLBACK(_settings_autoshow_change2), module);
   gtk_widget_set_tooltip_text(cb, _("show guide overlay when this module has focus"));
   GtkWidget *ic = dtgtk_button_new(dtgtk_cairo_paint_grid, 0, NULL);
   gtk_widget_set_tooltip_text
     (ic, _("change global guide settings\nnote that these settings are applied globally "
            "and will impact any module that shows guide overlays"));
-  g_signal_connect(G_OBJECT(ic), "clicked",
+  g_signal_connect(ic, "clicked",
                    G_CALLBACK(_settings_autoshow_menu), module);
 
   GtkWidget *box = dt_gui_hbox(dt_gui_expand(cb), ic);
diff --git a/src/gui/hist_dialog.c b/src/gui/hist_dialog.c
index 4b15472e9902..3f3663620c5d 100644
--- a/src/gui/hist_dialog.c
+++ b/src/gui/hist_dialog.c
@@ -143,10 +143,8 @@ static void _gui_hist_copy_response(GtkDialog *dialog,
 
 static void _gui_hist_item_toggled(GtkCellRendererToggle *cell,
                                    const gchar *path_str,
-                                   gpointer data)
+                                   dt_history_copy_item_t *d)
 {
-  dt_history_copy_item_t *d = (dt_history_copy_item_t *)data;
-
   const _styles_columns_t col =
     GPOINTER_TO_INT(g_object_get_data(G_OBJECT(cell), "column"));
 
@@ -274,7 +272,7 @@ int dt_gui_hist_dialog_new(dt_history_copy_item_t *d,
   GtkCellRenderer *renderer = gtk_cell_renderer_toggle_new();
   gtk_cell_renderer_toggle_set_activatable(GTK_CELL_RENDERER_TOGGLE(renderer), TRUE);
   g_object_set_data(G_OBJECT(renderer), "column", (gint *)DT_HIST_ITEMS_COL_ENABLED);
-  g_signal_connect(renderer, "toggled", G_CALLBACK(_gui_hist_item_toggled), d);
+  g_signal_connect(GTK_CELL_RENDERER_TOGGLE(renderer), "toggled", G_CALLBACK(_gui_hist_item_toggled), d);
 
   gtk_tree_view_insert_column_with_attributes
     (GTK_TREE_VIEW(d->items), -1, _("include"), renderer, "active",
@@ -284,7 +282,7 @@ int dt_gui_hist_dialog_new(dt_history_copy_item_t *d,
   renderer = gtk_cell_renderer_toggle_new();
   gtk_cell_renderer_toggle_set_activatable(GTK_CELL_RENDERER_TOGGLE(renderer), TRUE);
   g_object_set_data(G_OBJECT(renderer), "column", (gint *)DT_HIST_ITEMS_COL_AUTOINIT);
-  g_signal_connect(renderer, "toggled", G_CALLBACK(_gui_hist_item_toggled), d);
+  g_signal_connect(GTK_CELL_RENDERER_TOGGLE(renderer), "toggled", G_CALLBACK(_gui_hist_item_toggled), d);
 
   gtk_tree_view_insert_column_with_attributes(GTK_TREE_VIEW(d->items), -1, _("reset"),
                                               renderer, "active",
@@ -374,7 +372,7 @@ int dt_gui_hist_dialog_new(dt_history_copy_item_t *d,
   }
 
   g_signal_connect(GTK_TREE_VIEW(d->items), "row-activated",
-                   (GCallback)tree_on_row_activated, GTK_WIDGET(dialog));
+                   G_CALLBACK(tree_on_row_activated), GTK_WIDGET(dialog));
   g_object_unref(liststore);
 
   g_signal_connect(dialog, "response", G_CALLBACK(_gui_hist_copy_response), d);
diff --git a/src/gui/import_metadata.c b/src/gui/import_metadata.c
index a30ec603d09a..5fc8f054ea85 100644
--- a/src/gui/import_metadata.c
+++ b/src/gui/import_metadata.c
@@ -420,16 +420,16 @@ static void _fill_metadata_grid(dt_import_metadata_t *metadata)
     const char *str = dt_conf_get_string_const(setting);
     _set_up_entry(metadata_entry, str, metadata_name, i + DT_META_META_VALUE, metadata);
     g_free(setting);
-    g_signal_connect(GTK_ENTRY(metadata_entry), "changed",
+    g_signal_connect(metadata_entry, "changed",
                      G_CALLBACK(_import_metadata_changed), metadata);
-    g_signal_connect(GTK_EVENT_BOX(labelev), "button-press-event",
+    g_signal_connect(labelev, "button-press-event",
                      G_CALLBACK(_import_metadata_reset), metadata_entry);
 
     GtkWidget *metadata_imported = gtk_check_button_new();
     g_object_set_data(G_OBJECT(metadata_imported), "tagname", md->tagname);
     _set_up_toggle_button(metadata_imported, flag & DT_METADATA_FLAG_IMPORTED,
                           metadata_name, i + DT_META_META_VALUE, metadata);
-    g_signal_connect(GTK_TOGGLE_BUTTON(metadata_imported), "toggled",
+    g_signal_connect(metadata_imported, "toggled",
                      G_CALLBACK(_import_metadata_toggled), metadata);
     i++;
   }
diff --git a/src/gui/metadata_tags.c b/src/gui/metadata_tags.c
index 86d711ea93c9..08cccaa52324 100644
--- a/src/gui/metadata_tags.c
+++ b/src/gui/metadata_tags.c
@@ -102,7 +102,7 @@ GtkWidget *dt_metadata_tags_dialog(GtkWidget *parent, gpointer metadata_activate
   gtk_entry_set_text(GTK_ENTRY(sel_entry), "");
   gtk_widget_set_tooltip_text(sel_entry, _("list filter"));
   gtk_entry_set_activates_default(GTK_ENTRY(sel_entry), TRUE);
-  g_signal_connect(G_OBJECT(sel_entry), "changed", G_CALLBACK(_tag_name_changed), NULL);
+  g_signal_connect(sel_entry, "changed", G_CALLBACK(_tag_name_changed), NULL);
 
   sel_view = GTK_TREE_VIEW(gtk_tree_view_new());
   GtkWidget *w = dt_gui_scroll_wrap(GTK_WIDGET(sel_view));
@@ -150,7 +150,7 @@ GtkWidget *dt_metadata_tags_dialog(GtkWidget *parent, gpointer metadata_activate
   gtk_tree_sortable_set_sort_column_id(GTK_TREE_SORTABLE(liststore), DT_METADATA_TAGS_COL_XMP, GTK_SORT_ASCENDING);
   gtk_tree_view_set_model(sel_view, model);
   g_object_unref(model);
-  g_signal_connect(G_OBJECT(sel_view), "row-activated", G_CALLBACK(metadata_activated_callback), user_data);
+  g_signal_connect(sel_view, "row-activated", G_CALLBACK(metadata_activated_callback), user_data);
 
   dt_gui_dialog_add(GTK_DIALOG(dialog), sel_entry, w);
   return dialog;
diff --git a/src/gui/preferences.c b/src/gui/preferences.c
index d839bb1257f2..98634ca41a7a 100644
--- a/src/gui/preferences.c
+++ b/src/gui/preferences.c
@@ -353,8 +353,8 @@ static void init_tab_general(GtkWidget *dialog,
 
   dt_bauhaus_combobox_set(widget, darktable.l10n->selected);
   dt_bauhaus_combobox_set_default(widget, darktable.l10n->sys_default);
-  g_signal_connect(G_OBJECT(widget), "value-changed",
-                   G_CALLBACK(language_callback), 0);
+  g_signal_connect(widget, "value-changed",
+                   G_CALLBACK(language_callback), NULL);
   gtk_widget_set_tooltip_text(labelev,  _("double-click to reset to the system language"));
   gtk_event_box_set_visible_window(GTK_EVENT_BOX(labelev), FALSE);
   gtk_widget_set_tooltip_text(widget,
@@ -363,8 +363,8 @@ static void init_tab_general(GtkWidget *dialog,
                                 "(restart required)"));
   gtk_grid_attach(GTK_GRID(grid), labelev, 0, line++, 1, 1);
   gtk_grid_attach_next_to(GTK_GRID(grid), widget, labelev, GTK_POS_RIGHT, 1, 1);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event",
-                   G_CALLBACK(reset_language_widget), (gpointer)widget);
+  g_signal_connect(labelev, "button-press-event",
+                   G_CALLBACK(reset_language_widget), widget);
 
   // theme
 
@@ -399,7 +399,7 @@ static void init_tab_general(GtkWidget *dialog,
 
   dt_bauhaus_combobox_set(widget, selected);
 
-  g_signal_connect(G_OBJECT(widget), "value-changed",
+  g_signal_connect(widget, "value-changed",
                    G_CALLBACK(theme_callback), 0);
   gtk_widget_set_tooltip_text(widget, _("set the theme for the user interface"));
 
@@ -426,10 +426,10 @@ static void init_tab_general(GtkWidget *dialog,
   gtk_widget_set_tooltip_text(usesysfont, _("use system font size"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(usesysfont),
                                dt_conf_get_bool("use_system_font"));
-  g_signal_connect(G_OBJECT(usesysfont), "toggled",
-                   G_CALLBACK(use_sys_font_callback), (gpointer)fontsize);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event",
-                   G_CALLBACK(_gui_preferences_bool_click), (gpointer)usesysfont);
+  g_signal_connect(usesysfont, "toggled",
+                   G_CALLBACK(use_sys_font_callback), fontsize);
+  g_signal_connect(labelev, "button-press-event",
+                   G_CALLBACK(_gui_preferences_bool_click), usesysfont);
 
 
   //font size selector
@@ -448,7 +448,7 @@ static void init_tab_general(GtkWidget *dialog,
   gtk_grid_attach_next_to(GTK_GRID(grid), fontsize, labelev, GTK_POS_RIGHT, 1, 1);
   gtk_widget_set_tooltip_text(fontsize, _("font size in points"));
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(fontsize), dt_conf_get_float("font_size"));
-  g_signal_connect(G_OBJECT(fontsize), "value_changed",
+  g_signal_connect(fontsize, "value-changed",
                    G_CALLBACK(font_size_changed_callback), 0);
 
   GtkWidget *screen_dpi_overwrite = gtk_spin_button_new_with_range(-1.0f, 360, 1.f);
@@ -469,7 +469,7 @@ static void init_tab_general(GtkWidget *dialog,
        "(restart required)"));
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(screen_dpi_overwrite),
                             dt_conf_get_float("screen_dpi_overwrite"));
-  g_signal_connect(G_OBJECT(screen_dpi_overwrite), "value_changed",
+  g_signal_connect(screen_dpi_overwrite, "value-changed",
                    G_CALLBACK(dpi_scaling_changed_callback), 0);
 
   GtkWidget *panel_reset = gtk_button_new_with_label(_("reset view panels"));
@@ -494,10 +494,10 @@ static void init_tab_general(GtkWidget *dialog,
                               _("modify theme with CSS keyed below (saved to user.css)"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(tw->apply_toggle),
                                dt_conf_get_bool("themes/usercss"));
-  g_signal_connect(G_OBJECT(tw->apply_toggle), "toggled",
+  g_signal_connect(tw->apply_toggle, "toggled",
                    G_CALLBACK(usercss_callback), 0);
   g_signal_connect(G_OBJECT(labelev), "button-press-event",
-                   G_CALLBACK(_gui_preferences_bool_click), (gpointer)tw->apply_toggle);
+                   G_CALLBACK(_gui_preferences_bool_click), tw->apply_toggle);
 
   //scrollable textarea with save button to allow user to directly modify user.css file
   GtkWidget *usercssbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
@@ -516,9 +516,9 @@ static void init_tab_general(GtkWidget *dialog,
 
   GtkWidget *hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
   tw->save_button = gtk_button_new_with_label(C_("usercss", "save CSS and apply"));
-  g_signal_connect(G_OBJECT(tw->save_button), "clicked",
+  g_signal_connect(tw->save_button, "clicked",
                    G_CALLBACK(save_usercss_callback), tw);
-  g_signal_connect(G_OBJECT(dialog), "response",
+  g_signal_connect(dialog, "response",
                    G_CALLBACK(usercss_dialog_callback), tw);
   gtk_box_pack_end(GTK_BOX(hbox), tw->save_button, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(usercssbox), hbox, FALSE, FALSE, 0);
@@ -567,7 +567,7 @@ static void init_tab_general(GtkWidget *dialog,
 ///////////// end of gui and theme language selection
 
 
-void dt_gui_preferences_show()
+void dt_gui_preferences_show(void)
 {
   GtkWindow *win = GTK_WINDOW(dt_ui_main_window(darktable.gui->ui));
   _preferences_dialog =
@@ -985,30 +985,30 @@ static void init_tab_presets(GtkWidget *stack)
   GtkWidget *hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
   gtk_widget_set_name(hbox, "preset-controls");
 
-  GtkWidget *search_presets = gtk_search_entry_new();
-  gtk_box_pack_start(GTK_BOX(hbox), search_presets, FALSE, TRUE, 0);
+  GtkSearchEntry *search_presets = GTK_SEARCH_ENTRY(gtk_search_entry_new());
+  dt_gui_box_add(hbox, search_presets);
   gtk_entry_set_placeholder_text(GTK_ENTRY(search_presets), _("search presets list"));
   gtk_widget_set_tooltip_text
     (GTK_WIDGET(search_presets),
      _("incrementally search the list of presets\n"
        "press up or down keys to cycle through matches"));
-  g_signal_connect(G_OBJECT(search_presets), "activate",
+  g_signal_connect(search_presets, "activate",
                    G_CALLBACK(dt_gui_search_stop), tree);
-  g_signal_connect(G_OBJECT(search_presets), "stop-search",
+  g_signal_connect(search_presets, "stop-search",
                    G_CALLBACK(dt_gui_search_stop), tree);
-  g_signal_connect(G_OBJECT(tree), "key-press-event",
+  g_signal_connect(tree, "key-press-event",
                    G_CALLBACK(dt_gui_search_start), search_presets);
   gtk_tree_view_set_search_entry(tree, GTK_ENTRY(search_presets));
 
   GtkWidget *button = gtk_button_new_with_label(C_("preferences", "import..."));
   gtk_box_pack_end(GTK_BOX(hbox), button, FALSE, TRUE, 0);
-  g_signal_connect(G_OBJECT(button), "clicked",
-                   G_CALLBACK(import_preset), (gpointer)model);
+  g_signal_connect(button, "clicked",
+                   G_CALLBACK(import_preset), model);
 
   button = gtk_button_new_with_label(C_("preferences", "export..."));
   gtk_box_pack_end(GTK_BOX(hbox), button, FALSE, TRUE, 0);
-  g_signal_connect(G_OBJECT(button), "clicked",
-                   G_CALLBACK(export_preset), (gpointer)model);
+  g_signal_connect(button, "clicked",
+                   G_CALLBACK(export_preset), model);
 
   button = gtk_button_new_with_label(_("?"));
   dt_gui_add_help_link(button, "presets");
@@ -1018,12 +1018,12 @@ static void init_tab_presets(GtkWidget *stack)
   // Attaching treeview signals
 
   // row-activated either expands/collapses a row or activates editing
-  g_signal_connect(G_OBJECT(tree), "row-activated",
+  g_signal_connect(tree, "row-activated",
                    G_CALLBACK(tree_row_activated_presets), NULL);
 
   // A keypress may delete preset
-  g_signal_connect(G_OBJECT(tree), "key-press-event",
-                   G_CALLBACK(tree_key_press_presets), (gpointer)model);
+  g_signal_connect(tree, "key-press-event",
+                   G_CALLBACK(tree_key_press_presets), model);
 
   // Setting up the search functionality
   gtk_tree_view_set_search_equal_func(tree, _search_func, tree, NULL);
@@ -1372,10 +1372,10 @@ GtkWidget *dt_gui_preferences_bool(GtkGrid *grid,
 
   gtk_grid_attach(GTK_GRID(grid), labelev, swap ? (col + 1) : col, line, 1, 1);
   gtk_grid_attach(GTK_GRID(grid), w, swap ? col : (col + 1), line, 1, 1);
-  g_signal_connect(G_OBJECT(w), "toggled",
+  g_signal_connect(w, "toggled",
                    G_CALLBACK(_gui_preferences_bool_callback), (gpointer)key);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event",
-                   G_CALLBACK(_gui_preferences_bool_click), (gpointer)w);
+  g_signal_connect(labelev, "button-press-event",
+                   G_CALLBACK(_gui_preferences_bool_click), w);
   return w;
 }
 
@@ -1433,10 +1433,10 @@ GtkWidget *dt_gui_preferences_int(GtkGrid *grid,
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(w), dt_conf_get_int(key));
   gtk_grid_attach(GTK_GRID(grid), labelev, col, line, 1, 1);
   gtk_grid_attach(GTK_GRID(grid), w, col + 1, line, 1, 1);
-  g_signal_connect(G_OBJECT(w), "value-changed",
+  g_signal_connect(w, "value-changed",
                    G_CALLBACK(_gui_preferences_int_callback), (gpointer)key);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event",
-                   G_CALLBACK(_gui_preferences_int_reset), (gpointer)w);
+  g_signal_connect(labelev, "button-press-event",
+                   G_CALLBACK(_gui_preferences_int_reset), w);
   return w;
 }
 
@@ -1485,7 +1485,7 @@ GtkWidget *dt_gui_preferences_enum(dt_action_t *action,
     i++;
   }
 
-  g_signal_connect(G_OBJECT(w), "value-changed",
+  g_signal_connect(w, "value-changed",
                    G_CALLBACK(_gui_preferences_enum_callback), (gpointer)key);
   return w;
 }
@@ -1544,10 +1544,10 @@ GtkWidget *dt_gui_preferences_string(GtkGrid *grid,
 
   gtk_grid_attach(GTK_GRID(grid), labelev, col, line, 1, 1);
   gtk_grid_attach(GTK_GRID(grid), w, col + 1, line, 1, 1);
-  g_signal_connect(G_OBJECT(w), "changed",
+  g_signal_connect(w, "changed",
                    G_CALLBACK(_gui_preferences_string_callback), (gpointer)key);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event",
-                   G_CALLBACK(_gui_preferences_string_reset), (gpointer)w);
+  g_signal_connect(labelev, "button-press-event",
+                   G_CALLBACK(_gui_preferences_string_reset), w);
   return w;
 }
 
diff --git a/src/gui/preferences.h b/src/gui/preferences.h
index 096700541c32..9856e67953a0 100644
--- a/src/gui/preferences.h
+++ b/src/gui/preferences.h
@@ -19,7 +19,7 @@
 #pragma once
 
 /** shows the preferences dialog and blocks until it's closed. */
-void dt_gui_preferences_show();
+void dt_gui_preferences_show(void);
 
 // return the widget for a given preference key
 GtkWidget *dt_gui_preferences_bool(GtkGrid *grid, const char *key, const guint col,
diff --git a/src/gui/presets.c b/src/gui/presets.c
index 862839c7411b..bb95143dc490 100644
--- a/src/gui/presets.c
+++ b/src/gui/presets.c
@@ -634,9 +634,9 @@ static void _presets_show_edit_dialog(dt_gui_presets_edit_dialog_t *g,
     gtk_widget_set_sensitive(GTK_WIDGET(g->filter), TRUE);
   }
 
-  g_signal_connect(G_OBJECT(g->autoapply), "toggled",
+  g_signal_connect(g->autoapply, "toggled",
                    G_CALLBACK(_check_buttons_activated), g);
-  g_signal_connect(G_OBJECT(g->filter), "toggled",
+  g_signal_connect(g->filter, "toggled",
                    G_CALLBACK(_check_buttons_activated), g);
 
   int line = 0;
@@ -678,13 +678,13 @@ static void _presets_show_edit_dialog(dt_gui_presets_edit_dialog_t *g,
   gtk_widget_set_halign(label, GTK_ALIGN_START);
   g->iso_min = gtk_entry_new();
   gtk_widget_set_tooltip_text(g->iso_min, _("minimum ISO value"));
-  g_signal_connect(G_OBJECT(g->iso_min), "insert-text",
+  g_signal_connect(g->iso_min, "insert-text",
                    G_CALLBACK(_insert_text_event), NULL);
   g->iso_max = gtk_entry_new();
   gtk_widget_set_tooltip_text
     (g->iso_max,
      _("maximum ISO value\nif left blank, it is equivalent to no upper limit"));
-  g_signal_connect(G_OBJECT(g->iso_max), "insert-text",
+  g_signal_connect(g->iso_max, "insert-text",
                    G_CALLBACK(_insert_text_event), NULL);
   gtk_grid_attach(GTK_GRID(g->details), label, 0, line++, 1, 1);
   gtk_grid_attach_next_to(GTK_GRID(g->details), g->iso_min, label, GTK_POS_RIGHT, 2, 1);
@@ -981,7 +981,7 @@ static void _edit_preset(const char *name_in, dt_iop_module_t *module)
     name = g_strdup(name_in);
 
   dt_gui_presets_show_iop_edit_dialog
-    (name, module, (GCallback)_edit_preset_final_callback, NULL, TRUE, TRUE,
+    (name, module, G_CALLBACK(_edit_preset_final_callback), NULL, TRUE, TRUE,
      FALSE, GTK_WINDOW(dt_ui_main_window(darktable.gui->ui)));
   g_free(name);
 }
@@ -1336,13 +1336,13 @@ static void _menuitem_connect_preset(GtkWidget *mi,
   g_object_set_data_full(G_OBJECT(mi), "dt-preset-name", g_strdup(name), g_free);
   g_object_set_data(G_OBJECT(mi), "dt-preset-module", iop);
   dt_action_define(&iop->so->actions, "preset", name, mi, NULL);
-  g_signal_connect(G_OBJECT(mi), "activate",
+  g_signal_connect(mi, "activate",
                    G_CALLBACK(_menuitem_activate_preset), iop);
-  g_signal_connect(G_OBJECT(mi), "button-press-event",
+  g_signal_connect(mi, "button-press-event",
                    G_CALLBACK(_menuitem_button_preset), iop);
-  g_signal_connect(G_OBJECT(mi), "button-release-event",
+  g_signal_connect(mi, "button-release-event",
                    G_CALLBACK(_menuitem_button_preset), iop);
-  g_signal_connect(G_OBJECT(mi), "motion-notify-event",
+  g_signal_connect(mi, "motion-notify-event",
                    G_CALLBACK(_menuitem_motion_preset), iop);
   gtk_widget_set_has_tooltip(mi, TRUE);
 }
@@ -1611,7 +1611,7 @@ void dt_gui_favorite_presets_menu_show(GtkWidget *w)
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), gtk_separator_menu_item_new());
   GtkMenuItem *smi_manage = (GtkMenuItem *)gtk_menu_item_new_with_label
     (_("manage quick presets list..."));
-  g_signal_connect(G_OBJECT(smi_manage), "activate",
+  g_signal_connect(smi_manage, "activate",
                    G_CALLBACK(_menuitem_manage_quick_presets), NULL);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), GTK_WIDGET(smi_manage));
 
@@ -1797,19 +1797,19 @@ GtkMenu *dt_gui_presets_popup_menu_show_for_module(dt_iop_module_t *module)
     if(active_preset >= 0 && !writeprotect)
     {
       mi = gtk_menu_item_new_with_label(_("edit this preset.."));
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(_menuitem_edit_preset), module);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
       mi = gtk_menu_item_new_with_label(_("delete this preset"));
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(_menuitem_delete_preset), module);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
     }
     else
     {
       mi = gtk_menu_item_new_with_label(_("store new preset.."));
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(_menuitem_new_preset), module);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
@@ -1825,7 +1825,7 @@ GtkMenu *dt_gui_presets_popup_menu_show_for_module(dt_iop_module_t *module)
         gtk_label_set_markup(GTK_LABEL(gtk_bin_get_child(GTK_BIN(mi))), markup);
         g_object_set_data_full(G_OBJECT(mi), "dt-preset-name",
                                g_strdup(darktable.gui->last_preset), g_free);
-        g_signal_connect(G_OBJECT(mi), "activate",
+        g_signal_connect(mi, "activate",
                          G_CALLBACK(_menuitem_update_preset), module);
         gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
         g_free(markup);
diff --git a/src/gui/styles_dialog.c b/src/gui/styles_dialog.c
index 6eec005c8c1d..66bcb2de024d 100644
--- a/src/gui/styles_dialog.c
+++ b/src/gui/styles_dialog.c
@@ -356,10 +356,8 @@ static void _gui_styles_edit_style_response(GtkDialog *dialog,
 
 static void _gui_styles_item_toggled(GtkCellRendererToggle *cell,
                                      gchar *path_str,
-                                     gpointer data)
+                                     dt_gui_styles_dialog_t *sd)
 {
-  dt_gui_styles_dialog_t *sd = (dt_gui_styles_dialog_t *)data;
-
   GtkTreeModel *model = gtk_tree_view_get_model(GTK_TREE_VIEW(sd->items));
   GtkTreePath *path = gtk_tree_path_new_from_string(path_str);
   GtkTreeIter iter;
@@ -571,7 +569,7 @@ static gboolean _gui_styles_dialog_run(const gboolean edit,
   gtk_widget_set_tooltip_text(sd->name, _("enter a name for the new style"));
   gtk_entry_set_activates_default(GTK_ENTRY(sd->name), TRUE);
   gtk_dialog_set_response_sensitive(dialog, GTK_RESPONSE_ACCEPT, FALSE);
-  g_signal_connect(sd->name, "changed", G_CALLBACK(_name_changed), dialog);
+  g_signal_connect(GTK_ENTRY(sd->name), "changed", G_CALLBACK(_name_changed), dialog);
 
   sd->description = gtk_entry_new();
   gtk_entry_set_placeholder_text(GTK_ENTRY(sd->description), _("description"));
@@ -613,7 +611,7 @@ static gboolean _gui_styles_dialog_run(const gboolean edit,
   GtkCellRenderer *renderer = gtk_cell_renderer_toggle_new();
   gtk_cell_renderer_toggle_set_activatable(GTK_CELL_RENDERER_TOGGLE(renderer), TRUE);
   g_object_set_data(G_OBJECT(renderer), "column", (gint *)DT_STYLE_ITEMS_COL_ENABLED);
-  g_signal_connect(renderer, "toggled", G_CALLBACK(_gui_styles_item_toggled), sd);
+  g_signal_connect(GTK_CELL_RENDERER_TOGGLE(renderer), "toggled", G_CALLBACK(_gui_styles_item_toggled), sd);
   gtk_tree_view_insert_column_with_attributes(GTK_TREE_VIEW(sd->items), -1,
                                               edit ? _("keep") : _("include"),
                                               renderer, "active",
@@ -1030,7 +1028,7 @@ GtkWidget *dt_gui_style_content_dialog(char *name, const dt_imgid_t imgid)
     gtk_widget_set_app_paintable(da, TRUE);
     gtk_box_pack_start(GTK_BOX(ht), da, TRUE, TRUE, 0);
     data.first_draw = TRUE;
-    g_signal_connect(G_OBJECT(da), "draw", G_CALLBACK(_preview_draw), &data);
+    g_signal_connect(da, "draw", G_CALLBACK(_preview_draw), &data);
   }
 
   return ht;
diff --git a/src/gui/workspace.c b/src/gui/workspace.c
index 605d227bccec..337b1a061645 100644
--- a/src/gui/workspace.c
+++ b/src/gui/workspace.c
@@ -134,7 +134,7 @@ static GtkBox *_insert_button(dt_workspace_t *session, const char *label)
   GtkWidget *b = gtk_button_new_with_label(label);
   gtk_widget_set_hexpand(GTK_WIDGET(b), TRUE);
   dt_gui_box_add(box, b);
-  g_signal_connect(G_OBJECT(b), "clicked",
+  g_signal_connect(b, "clicked",
                    G_CALLBACK(_workspace_select_db), session);
   dt_gui_dialog_add(session->db_screen, box);
   return box;
@@ -215,7 +215,7 @@ void dt_workspace_create(const char *datadir)
       g_list_free(bc);
 
       GtkWidget *del = dtgtk_button_new(dtgtk_cairo_paint_remove, 0, NULL);
-      g_signal_connect(G_OBJECT(del), "clicked",
+      g_signal_connect(del, "clicked",
                        G_CALLBACK(_workspace_delete_db), session);
       g_object_set_data(G_OBJECT(del), "db", b);
       dt_gui_box_add(box, del);
@@ -235,14 +235,14 @@ void dt_workspace_create(const char *datadir)
 
   GtkBox *box = GTK_BOX(dt_gui_hbox());
   session->entry = gtk_entry_new();
-  g_signal_connect(G_OBJECT(session->entry),
+  g_signal_connect(session->entry,
                    "changed", G_CALLBACK(_workspace_entry_changed), session);
   gtk_widget_set_hexpand(session->entry, TRUE);
 
   session->create = gtk_button_new_with_label(_("create"));
   gtk_widget_set_sensitive(session->create, FALSE);
 
-  g_signal_connect(G_OBJECT(session->create), "clicked",
+  g_signal_connect(session->create, "clicked",
                    G_CALLBACK(_workspace_new_db), session);
   dt_gui_box_add(box, session->entry, session->create);
   gtk_widget_set_hexpand(GTK_WIDGET(box), TRUE);
diff --git a/src/imageio/format/avif.c b/src/imageio/format/avif.c
index a5b2bea2cb3b..7065e2c44e1b 100644
--- a/src/imageio/format/avif.c
+++ b/src/imageio/format/avif.c
@@ -1031,15 +1031,15 @@ void gui_init(dt_imageio_module_format_t *self)
   gtk_widget_set_visible(gui->subsample, compression_type != AVIF_COMP_LOSSLESS);
   gtk_widget_set_no_show_all(gui->subsample, TRUE);
 
-  g_signal_connect(G_OBJECT(gui->bit_depth),
+  g_signal_connect(gui->bit_depth,
                    "value-changed",
                    G_CALLBACK(bit_depth_changed),
                    NULL);
-  g_signal_connect(G_OBJECT(gui->compression_type),
+  g_signal_connect(gui->compression_type,
                    "value-changed",
                    G_CALLBACK(compression_type_changed),
                    (gpointer)self);
-  g_signal_connect(G_OBJECT(gui->quality),
+  g_signal_connect(gui->quality,
                    "value-changed",
                    G_CALLBACK(quality_changed),
                    NULL);
diff --git a/src/imageio/format/j2k.c b/src/imageio/format/j2k.c
index 4c09adac4422..f16afe91d6ba 100644
--- a/src/imageio/format/j2k.c
+++ b/src/imageio/format/j2k.c
@@ -706,7 +706,7 @@ void gui_init(dt_imageio_module_format_t *self)
                                                   0);
   dt_bauhaus_widget_set_label(gui->quality, NULL, N_("quality"));
   dt_bauhaus_slider_set(gui->quality, quality_last);
-  g_signal_connect(G_OBJECT(gui->quality), "value-changed", G_CALLBACK(quality_changed), NULL);
+  g_signal_connect(gui->quality, "value-changed", G_CALLBACK(quality_changed), NULL);
 
   DT_BAUHAUS_COMBOBOX_NEW_FULL(gui->preset, self, NULL, N_("DCP mode"), NULL,
                                preset_last, preset_changed, self,
diff --git a/src/imageio/format/jpeg.c b/src/imageio/format/jpeg.c
index 3f73e132c931..3ae10e2e7445 100644
--- a/src/imageio/format/jpeg.c
+++ b/src/imageio/format/jpeg.c
@@ -577,7 +577,7 @@ void gui_init(dt_imageio_module_format_t *self)
 
   dt_bauhaus_widget_set_label(g->quality, NULL, N_("quality"));
   dt_bauhaus_slider_set(g->quality, dt_conf_get_int("plugins/imageio/format/jpeg/quality"));
-  g_signal_connect(G_OBJECT(g->quality), "value-changed",
+  g_signal_connect(g->quality, "value-changed",
                    G_CALLBACK(quality_changed), NULL);
 
   DT_BAUHAUS_COMBOBOX_NEW_FULL
diff --git a/src/imageio/format/jxl.c b/src/imageio/format/jxl.c
index c81b47d9dcbe..84224219f946 100644
--- a/src/imageio/format/jxl.c
+++ b/src/imageio/format/jxl.c
@@ -606,7 +606,7 @@ void gui_init(dt_imageio_module_format_t *self)
   gtk_widget_set_tooltip_text(gui->quality,
                               _("the quality of the output image\n0-29 = very lossy\n30-99 = JPEG "
                                 "quality comparable\n100 = lossless"));
-  g_signal_connect(G_OBJECT(gui->quality), "value-changed", G_CALLBACK(quality_changed), gui);
+  g_signal_connect(gui->quality, "value-changed", G_CALLBACK(quality_changed), gui);
 
   // encoding color profile combobox
   const int original = dt_conf_get_bool("plugins/imageio/format/jxl/original") & 1;
@@ -634,7 +634,7 @@ void gui_init(dt_imageio_module_format_t *self)
   gtk_widget_set_tooltip_text(gui->effort,
                               _("the effort used to encode the image, higher efforts will have "
                                 "better results at the expense of longer encoding times"));
-  g_signal_connect(G_OBJECT(gui->effort), "value-changed", G_CALLBACK(effort_changed), NULL);
+  g_signal_connect(gui->effort, "value-changed", G_CALLBACK(effort_changed), NULL);
 
   // decoding speed (tier) slider
   gui->tier = dt_bauhaus_slider_new_with_range(
@@ -645,7 +645,7 @@ void gui_init(dt_imageio_module_format_t *self)
   dt_bauhaus_widget_set_label(gui->tier, NULL, N_("decoding speed"));
   gtk_widget_set_tooltip_text(gui->tier,
                               _("the preferred decoding speed with some sacrifice of quality"));
-  g_signal_connect(G_OBJECT(gui->tier), "value-changed", G_CALLBACK(tier_changed), NULL);
+  g_signal_connect(gui->tier, "value-changed", G_CALLBACK(tier_changed), NULL);
 
   self->widget = dt_gui_vbox(gui->bpp, gui->pixel_type, gui->quality,
                              gui->original, gui->effort, gui->tier);
diff --git a/src/imageio/format/pdf.c b/src/imageio/format/pdf.c
index 16fa16531ece..d7ad7ae08d30 100644
--- a/src/imageio/format/pdf.c
+++ b/src/imageio/format/pdf.c
@@ -641,7 +641,7 @@ void gui_init(dt_imageio_module_format_t *self)
   gtk_grid_attach(grid, GTK_WIDGET(d->dpi), 1, line, 1, 1);
   gtk_widget_set_tooltip_text(GTK_WIDGET(d->dpi), _("dpi of the images inside the PDF"));
   gtk_spin_button_set_value(d->dpi, dt_conf_get_float("plugins/imageio/format/pdf/dpi"));
-  g_signal_connect(G_OBJECT(d->dpi), "value-changed", G_CALLBACK(dpi_changed_callback), self);
+  g_signal_connect(d->dpi, "value-changed", G_CALLBACK(dpi_changed_callback), self);
 
   // rotate images yes|no
 
@@ -684,7 +684,7 @@ void gui_init(dt_imageio_module_format_t *self)
     if(_pdf_bpp[i].bpp == bpp) sel = i;
   }
   gtk_grid_attach(grid, GTK_WIDGET(d->bpp), 0, ++line, 2, 1);
-  g_signal_connect(G_OBJECT(d->bpp), "value-changed", G_CALLBACK(bpp_toggle_callback), self);
+  g_signal_connect(d->bpp, "value-changed", G_CALLBACK(bpp_toggle_callback), self);
   gtk_widget_set_tooltip_text(d->bpp, _("bits per channel of the embedded images"));
   dt_bauhaus_combobox_set(d->bpp, sel);
 
diff --git a/src/imageio/format/png.c b/src/imageio/format/png.c
index 6b8179219c95..bd0713396b5c 100644
--- a/src/imageio/format/png.c
+++ b/src/imageio/format/png.c
@@ -701,7 +701,7 @@ void gui_init(dt_imageio_module_format_t *self)
      0);
   dt_bauhaus_widget_set_label(gui->compression, NULL, N_("compression"));
   dt_bauhaus_slider_set(gui->compression, compression);
-  g_signal_connect(G_OBJECT(gui->compression), "value-changed",
+  g_signal_connect(gui->compression, "value-changed",
                    G_CALLBACK(compression_level_changed), NULL);
 
   self->widget = dt_gui_vbox(gui->bit_depth, gui->compression);
diff --git a/src/imageio/format/tiff.c b/src/imageio/format/tiff.c
index 2d5a9dd4609f..13acafd6c1c8 100644
--- a/src/imageio/format/tiff.c
+++ b/src/imageio/format/tiff.c
@@ -910,7 +910,7 @@ void gui_init(dt_imageio_module_format_t *self)
       dt_confgen_get_int("plugins/imageio/format/tiff/compresslevel", DT_DEFAULT), 0);
   dt_bauhaus_widget_set_label(gui->compresslevel, NULL, N_("compression level"));
   dt_bauhaus_slider_set(gui->compresslevel, compresslevel);
-  g_signal_connect(G_OBJECT(gui->compresslevel), "value-changed", G_CALLBACK(compress_level_changed), NULL);
+  g_signal_connect(gui->compresslevel, "value-changed", G_CALLBACK(compress_level_changed), NULL);
 
   gtk_widget_set_visible(gui->compresslevel, compress != 0);
   gtk_widget_set_no_show_all(gui->compresslevel, TRUE);
diff --git a/src/imageio/format/webp.c b/src/imageio/format/webp.c
index a2d82d645987..69f205cf7cf5 100644
--- a/src/imageio/format/webp.c
+++ b/src/imageio/format/webp.c
@@ -421,7 +421,7 @@ void gui_init(dt_imageio_module_format_t *self)
                                               "for lossless, 0 is the fastest but gives larger files compared\n"
                                               "to the slowest 100."));
   dt_bauhaus_slider_set(gui->quality, quality);
-  g_signal_connect(G_OBJECT(gui->quality), "value-changed", G_CALLBACK(quality_changed), NULL);
+  g_signal_connect(gui->quality, "value-changed", G_CALLBACK(quality_changed), NULL);
 
   gtk_widget_set_visible(gui->quality, comp_type != webp_lossless);
   gtk_widget_set_no_show_all(gui->quality, TRUE);
diff --git a/src/imageio/storage/disk.c b/src/imageio/storage/disk.c
index 36bd4675be09..5bde983ac6ea 100644
--- a/src/imageio/storage/disk.c
+++ b/src/imageio/storage/disk.c
@@ -281,7 +281,7 @@ void gui_init(dt_imageio_module_storage_t *self)
   GtkWidget *widget = dtgtk_button_new(dtgtk_cairo_paint_directory, CPF_NONE, NULL);
   gtk_widget_set_name(widget, "non-flat");
   gtk_widget_set_tooltip_text(widget, _("select directory"));
-  g_signal_connect(G_OBJECT(widget), "clicked", G_CALLBACK(button_clicked), self);
+  g_signal_connect(widget, "clicked", G_CALLBACK(button_clicked), self);
 
   DT_BAUHAUS_COMBOBOX_NEW_FULL(d->onsave_action, self, NULL, N_("on conflict"), NULL,
                                dt_conf_get_int("plugins/imageio/storage/disk/overwrite"),
diff --git a/src/imageio/storage/gallery.c b/src/imageio/storage/gallery.c
index 5b6549d5372e..8d7febe7a772 100644
--- a/src/imageio/storage/gallery.c
+++ b/src/imageio/storage/gallery.c
@@ -205,7 +205,7 @@ void gui_init(dt_imageio_module_storage_t *self)
   GtkWidget *widget = dtgtk_button_new(dtgtk_cairo_paint_directory, CPF_NONE, NULL);
   gtk_widget_set_name(widget, "non-flat");
   gtk_widget_set_tooltip_text(widget, _("select directory"));
-  g_signal_connect(G_OBJECT(widget), "clicked", G_CALLBACK(button_clicked), self);
+  g_signal_connect(widget, "clicked", G_CALLBACK(button_clicked), self);
 
   d->title_entry =
     GTK_ENTRY(dt_action_entry_new
diff --git a/src/imageio/storage/latex.c b/src/imageio/storage/latex.c
index b3d7b441ac30..aff35e4f841c 100644
--- a/src/imageio/storage/latex.c
+++ b/src/imageio/storage/latex.c
@@ -191,7 +191,7 @@ void gui_init(dt_imageio_module_storage_t *self)
   GtkWidget *widget = dtgtk_button_new(dtgtk_cairo_paint_directory, CPF_NONE, NULL);
   gtk_widget_set_name(widget, "non-flat");
   gtk_widget_set_tooltip_text(widget, _("select directory"));
-  g_signal_connect(G_OBJECT(widget), "clicked", G_CALLBACK(button_clicked), self);
+  g_signal_connect(widget, "clicked", G_CALLBACK(button_clicked), self);
 
   d->title_entry = GTK_ENTRY(dt_action_entry_new(DT_ACTION(self), N_("path"), G_CALLBACK(title_changed_callback), self,
                                            _("enter the title of the book"),
diff --git a/src/imageio/storage/piwigo.c b/src/imageio/storage/piwigo.c
index 138467ec737f..146b33f81596 100644
--- a/src/imageio/storage/piwigo.c
+++ b/src/imageio/storage/piwigo.c
@@ -1058,7 +1058,7 @@ void gui_init(dt_imageio_module_storage_t *self)
     index++;
   }
   gtk_widget_set_hexpand(ui->account_list, TRUE);
-  g_signal_connect(G_OBJECT(ui->account_list), "value-changed",
+  g_signal_connect(ui->account_list, "value-changed",
                    G_CALLBACK(_piwigo_account_changed), (gpointer)ui);
 
   // server
@@ -1100,7 +1100,7 @@ void gui_init(dt_imageio_module_storage_t *self)
   // login button
   GtkWidget *login_button = gtk_button_new_with_label(_("login"));
   gtk_widget_set_tooltip_text(login_button, _("Piwigo login"));
-  g_signal_connect(G_OBJECT(login_button), "clicked",
+  g_signal_connect(login_button, "clicked",
                    G_CALLBACK(_piwigo_login_clicked), self);
 
   // status area
@@ -1125,13 +1125,13 @@ void gui_init(dt_imageio_module_storage_t *self)
   ui->album_list = dt_bauhaus_combobox_new_action(DT_ACTION(self)); // Available albums
   dt_bauhaus_widget_set_label(ui->album_list, NULL, N_("album"));
   gtk_widget_set_hexpand(GTK_WIDGET(ui->album_list), TRUE);
-  g_signal_connect(G_OBJECT(ui->album_list), "value-changed",
+  g_signal_connect(ui->album_list, "value-changed",
                    G_CALLBACK(_piwigo_album_changed), (gpointer)ui);
   gtk_widget_set_sensitive(ui->album_list, FALSE);
 
   GtkWidget *refresh_button = dtgtk_button_new(dtgtk_cairo_paint_refresh, CPF_NONE, NULL);
   gtk_widget_set_tooltip_text(refresh_button, _("refresh album list"));
-  g_signal_connect(G_OBJECT(refresh_button), "clicked",
+  g_signal_connect(refresh_button, "clicked",
                    G_CALLBACK(_piwigo_refresh_clicked), (gpointer)ui);
 
   // new album
@@ -1174,7 +1174,7 @@ void gui_init(dt_imageio_module_storage_t *self)
   dt_bauhaus_combobox_add(ui->conflict_action, _("skip"));
   dt_bauhaus_combobox_add(ui->conflict_action, _("update metadata"));
   dt_bauhaus_combobox_add(ui->conflict_action, _("overwrite"));
-  g_signal_connect(G_OBJECT(ui->conflict_action), "value-changed",
+  g_signal_connect(ui->conflict_action, "value-changed",
                    G_CALLBACK(_piwigo_conflict_changed), self);
   dt_bauhaus_combobox_set(ui->conflict_action, dt_conf_get_int("storage/piwigo/conflict"));
 
diff --git a/src/iop/agx.c b/src/iop/agx.c
index 99f6174e6f47..ce27639126f6 100644
--- a/src/iop/agx.c
+++ b/src/iop/agx.c
@@ -1928,7 +1928,7 @@ static GtkWidget* _create_curve_graph_box(dt_iop_module_t *self,
   g_object_set_data(G_OBJECT(g->graph_drawing_area), "iop-instance", self);
   dt_action_define_iop(self, N_("curve"), N_("graph"), GTK_WIDGET(g->graph_drawing_area), NULL);
   gtk_widget_set_can_focus(GTK_WIDGET(g->graph_drawing_area), TRUE);
-  g_signal_connect(G_OBJECT(g->graph_drawing_area), "draw", G_CALLBACK(_agx_draw_curve), self);
+  g_signal_connect(g->graph_drawing_area, "draw", G_CALLBACK(_agx_draw_curve), self);
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->graph_drawing_area), _("tone mapping curve"));
 
   // Pack drawing area at the top
@@ -2054,7 +2054,7 @@ static void _add_exposure_box(dt_iop_module_t *self, dt_iop_agx_gui_data_t *g, d
 
   g->btn_read_exposure = dtgtk_button_new(dtgtk_cairo_paint_camera, 0, NULL);
   gtk_widget_set_tooltip_text(g->btn_read_exposure, _("read exposure from metadata and exposure module"));
-  g_signal_connect(G_OBJECT(g->btn_read_exposure), "clicked", G_CALLBACK(_read_exposure_params_callback), real_self);
+  g_signal_connect(g->btn_read_exposure, "clicked", G_CALLBACK(_read_exposure_params_callback), real_self);
   dt_action_define_iop(real_self, N_("exposure range"), N_("read exposure"), g->btn_read_exposure, &dt_action_def_button);
   dt_gui_box_add(g->range_exposure_picker_group, g->btn_read_exposure);
 
diff --git a/src/iop/ashift.c b/src/iop/ashift.c
index 0b5fd68efc27..58b31f26fbe6 100644
--- a/src/iop/ashift.c
+++ b/src/iop/ashift.c
@@ -5321,9 +5321,9 @@ static void cropmode_callback(GtkWidget *widget, dt_iop_module_t *self)
   _swap_shadow_crop_box(p,g);
 }
 
-static int _event_fit_v_button_clicked(GtkWidget *widget,
-                                       const GdkEventButton *event,
-                                       dt_iop_module_t *self)
+static gboolean _event_fit_v_button_clicked(GtkWidget *widget,
+                                            const GdkEventButton *event,
+                                            dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return FALSE;
 
@@ -5369,9 +5369,9 @@ static int _event_fit_v_button_clicked(GtkWidget *widget,
   return FALSE;
 }
 
-static int _event_fit_h_button_clicked(GtkWidget *widget,
-                                       const GdkEventButton *event,
-                                       dt_iop_module_t *self)
+static gboolean _event_fit_h_button_clicked(GtkWidget *widget,
+                                            const GdkEventButton *event,
+                                            dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return FALSE;
 
@@ -5417,9 +5417,9 @@ static int _event_fit_h_button_clicked(GtkWidget *widget,
   return FALSE;
 }
 
-static int _event_fit_both_button_clicked(GtkWidget *widget,
-                                          const GdkEventButton *event,
-                                          dt_iop_module_t *self)
+static gboolean _event_fit_both_button_clicked(GtkWidget *widget,
+                                               const GdkEventButton *event,
+                                               dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return FALSE;
 
@@ -5467,9 +5467,9 @@ static int _event_fit_both_button_clicked(GtkWidget *widget,
   return FALSE;
 }
 
-static int _event_structure_auto_clicked(GtkWidget *widget,
-                                         const GdkEventButton *event,
-                                         dt_iop_module_t *self)
+static gboolean _event_structure_auto_clicked(GtkWidget *widget,
+                                              const GdkEventButton *event,
+                                              dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return FALSE;
 
@@ -5856,9 +5856,9 @@ static float log2_curve(const float inval, const dt_bauhaus_curve_t dir)
   return outval;
 }
 
-static int _event_structure_quad_clicked(GtkWidget *widget,
-                                         GdkEventButton *event,
-                                         dt_iop_module_t *self)
+static gboolean _event_structure_quad_clicked(GtkWidget *widget,
+                                              GdkEventButton *event,
+                                              dt_iop_module_t *self)
 {
   dt_iop_ashift_gui_data_t *g = self->gui_data;
   if(darktable.gui->reset) return FALSE;
@@ -5884,9 +5884,9 @@ static int _event_structure_quad_clicked(GtkWidget *widget,
   return TRUE;
 }
 
-static int _event_structure_lines_clicked(GtkWidget *widget,
-                                          GdkEventButton *event,
-                                          dt_iop_module_t *self)
+static gboolean _event_structure_lines_clicked(GtkWidget *widget,
+                                               GdkEventButton *event,
+                                               dt_iop_module_t *self)
 {
   dt_iop_ashift_gui_data_t *g = self->gui_data;
   if(darktable.gui->reset) return FALSE;
@@ -5970,7 +5970,7 @@ void gui_init(dt_iop_module_t *self)
   dt_shortcut_register(ac, 0, 0, GDK_KEY_r, GDK_MOD1_MASK);
 
   g->cropmode = dt_bauhaus_combobox_from_params(self, "cropmode");
-  g_signal_connect(G_OBJECT(g->cropmode), "value-changed",
+  g_signal_connect(g->cropmode, "value-changed",
                    G_CALLBACK(cropmode_callback), self);
 
   GtkWidget *main_box = self->widget;
@@ -6111,25 +6111,25 @@ void gui_init(dt_iop_module_t *self)
     (g->structure_quad, _("manually define perspective rectangle"));
   gtk_widget_set_tooltip_text(g->structure_lines, _("manually draw structure lines"));
 
-  g_signal_connect(G_OBJECT(g->fit_v), "button-press-event",
+  g_signal_connect(g->fit_v, "button-press-event",
                    G_CALLBACK(_event_fit_v_button_clicked),
-                   (gpointer)self);
-  g_signal_connect(G_OBJECT(g->fit_h), "button-press-event",
+                   self);
+  g_signal_connect(g->fit_h, "button-press-event",
                    G_CALLBACK(_event_fit_h_button_clicked),
-                   (gpointer)self);
-  g_signal_connect(G_OBJECT(g->fit_both), "button-press-event",
+                   self);
+  g_signal_connect(g->fit_both, "button-press-event",
                    G_CALLBACK(_event_fit_both_button_clicked),
-                   (gpointer)self);
-  g_signal_connect(G_OBJECT(g->structure_quad), "button-press-event",
+                   self);
+  g_signal_connect(g->structure_quad, "button-press-event",
                    G_CALLBACK(_event_structure_quad_clicked),
-                   (gpointer)self);
-  g_signal_connect(G_OBJECT(g->structure_lines), "button-press-event",
+                   self);
+  g_signal_connect(g->structure_lines, "button-press-event",
                    G_CALLBACK(_event_structure_lines_clicked),
-                   (gpointer)self);
-  g_signal_connect(G_OBJECT(g->structure_auto), "button-press-event",
+                   self);
+  g_signal_connect(g->structure_auto, "button-press-event",
                    G_CALLBACK(_event_structure_auto_clicked),
-                   (gpointer)self);
-  g_signal_connect(G_OBJECT(self->widget), "draw", G_CALLBACK(_event_draw), self);
+                   self);
+  g_signal_connect(self->widget, "draw", G_CALLBACK(_event_draw), self);
 
   dt_action_define_iop(self, N_("fit"),
                        N_("vertical"), g->fit_v, &dt_action_def_button);
diff --git a/src/iop/atrous.c b/src/iop/atrous.c
index 1ea3d3282364..09d90d19fd53 100644
--- a/src/iop/atrous.c
+++ b/src/iop/atrous.c
@@ -1798,7 +1798,7 @@ void gui_init(dt_iop_module_t *self)
        " and chroma tabs"));
   gtk_widget_show(gtk_notebook_get_nth_page(g->channel_tabs, g->channel));
   gtk_notebook_set_current_page(g->channel_tabs, g->channel);
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page", G_CALLBACK(tab_switch), self);
+  g_signal_connect(g->channel_tabs, "switch-page", G_CALLBACK(tab_switch), self);
 
   // graph
   g->area = GTK_DRAWING_AREA(dt_ui_resize_wrap
@@ -1809,18 +1809,18 @@ void gui_init(dt_iop_module_t *self)
   g_object_set_data(G_OBJECT(g->area), "iop-instance", self);
   dt_action_define_iop(self, NULL, N_("graph"),
                        GTK_WIDGET(g->area), &_action_def_equalizer);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(area_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "draw", G_CALLBACK(area_draw), self);
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(area_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event",
+  g_signal_connect(g->area, "button-release-event",
                    G_CALLBACK(area_button_release), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(area_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(g->area, "leave-notify-event",
                    G_CALLBACK(area_enter_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "enter-notify-event",
+  g_signal_connect(g->area, "enter-notify-event",
                    G_CALLBACK(area_enter_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(area_scrolled), self);
 
   self->widget = dt_gui_vbox(g->channel_tabs, g->area);
@@ -1828,7 +1828,7 @@ void gui_init(dt_iop_module_t *self)
   // mix slider
   g->mix = dt_bauhaus_slider_from_params(self, N_("mix"));
   gtk_widget_set_tooltip_text(g->mix, _("make effect stronger or weaker"));
-  g_signal_connect(G_OBJECT(g->mix), "value-changed", G_CALLBACK(mix_callback), self);
+  g_signal_connect(g->mix, "value-changed", G_CALLBACK(mix_callback), self);
 }
 
 void gui_cleanup(dt_iop_module_t *self)
diff --git a/src/iop/basecurve.c b/src/iop/basecurve.c
index a222747199a6..c0e1d0c0d765 100644
--- a/src/iop/basecurve.c
+++ b/src/iop/basecurve.c
@@ -2156,19 +2156,19 @@ void gui_init(dt_iop_module_t *self)
 
   g->logbase = dt_bauhaus_slider_new_with_range(self, 0.0f, 40.0f, 0, 0.0f, 2);
   dt_bauhaus_widget_set_label(g->logbase, NULL, N_("scale for graph"));
-  g_signal_connect(G_OBJECT(g->logbase), "value-changed", G_CALLBACK(logbase_callback), self);
+  g_signal_connect(g->logbase, "value-changed", G_CALLBACK(logbase_callback), self);
   dt_gui_box_add(self->widget, g->logbase);
 
   gtk_widget_add_events(GTK_WIDGET(g->area), GDK_POINTER_MOTION_MASK | darktable.gui->scroll_mask
                                            | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                            | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_basecurve_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(dt_iop_basecurve_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(dt_iop_basecurve_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(dt_iop_basecurve_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event", G_CALLBACK(_scrolled), self);
-  g_signal_connect(G_OBJECT(g->area), "key-press-event", G_CALLBACK(dt_iop_basecurve_key_press), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_basecurve_draw), self);
+  g_signal_connect(g->area, "button-press-event", G_CALLBACK(dt_iop_basecurve_button_press), self);
+  g_signal_connect(g->area, "motion-notify-event", G_CALLBACK(dt_iop_basecurve_motion_notify), self);
+  g_signal_connect(g->area, "leave-notify-event", G_CALLBACK(dt_iop_basecurve_leave_notify), self);
+  g_signal_connect(g->area, "scroll-event", G_CALLBACK(_scrolled), self);
+  g_signal_connect(g->area, "key-press-event", G_CALLBACK(dt_iop_basecurve_key_press), self);
 }
 
 void gui_cleanup(dt_iop_module_t *self)
diff --git a/src/iop/basicadj.c b/src/iop/basicadj.c
index c9d20177f20c..fa79b0d59cac 100644
--- a/src/iop/basicadj.c
+++ b/src/iop/basicadj.c
@@ -639,7 +639,7 @@ void gui_init(dt_iop_module_t *self)
                       dt_bauhaus_slider_from_params(self, "middle_grey"));
   dt_bauhaus_slider_set_format(g->sl_middle_grey, "%");
   gtk_widget_set_tooltip_text(g->sl_middle_grey, _("middle gray adjustment"));
-  g_signal_connect(G_OBJECT(g->sl_middle_grey), "quad-pressed", G_CALLBACK(_color_picker_callback), self);
+  g_signal_connect(g->sl_middle_grey, "quad-pressed", G_CALLBACK(_color_picker_callback), self);
 
   g->sl_brightness = dt_bauhaus_slider_from_params(self, N_("brightness"));
   dt_bauhaus_slider_set_soft_range(g->sl_brightness, -1.0, 1.0);
@@ -660,7 +660,7 @@ void gui_init(dt_iop_module_t *self)
                               _("apply auto exposure based on a region defined by the user\n"
                                 "click and drag to draw the area\n"
                                 "right-click to cancel"));
-  g_signal_connect(G_OBJECT(g->bt_select_region), "toggled", G_CALLBACK(_select_region_toggled_callback), self);
+  g_signal_connect(g->bt_select_region, "toggled", G_CALLBACK(_select_region_toggled_callback), self);
 
   dt_gui_box_add(self->widget, dt_gui_expand(g->bt_auto_levels), dt_gui_expand(g->bt_select_region));
 
diff --git a/src/iop/blurs.c b/src/iop/blurs.c
index a54c887e6600..0957976906f9 100644
--- a/src/iop/blurs.c
+++ b/src/iop/blurs.c
@@ -771,7 +771,7 @@ void gui_init(dt_iop_module_t *self)
   g->img_width = 0.f;
 
   g->area = GTK_DRAWING_AREA(dtgtk_drawing_area_new_with_height(0));
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(_dt_iop_tonecurve_draw), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(_dt_iop_tonecurve_draw), self);
   self->widget = dt_gui_vbox(g->area);
 
   g->radius = dt_bauhaus_slider_from_params(self, "radius");
diff --git a/src/iop/borders.c b/src/iop/borders.c
index 4777c0299988..f99eec188976 100644
--- a/src/iop/borders.c
+++ b/src/iop/borders.c
@@ -854,8 +854,8 @@ void gui_changed(dt_iop_module_t *self,
   }
 }
 
-static void _colorpick_color_set(GtkColorButton *widget,
-                                dt_iop_module_t *self)
+static void _colorpick_color_set(GtkWidget *widget,
+                                 dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return;
   dt_iop_borders_params_t *p = self->params;
@@ -872,7 +872,8 @@ static void _colorpick_color_set(GtkColorButton *widget,
   dt_dev_add_history_item(darktable.develop, self, TRUE);
 }
 
-static void _frame_colorpick_color_set(GtkColorButton *widget, dt_iop_module_t *self)
+static void _frame_colorpick_color_set(GtkWidget *widget,
+                                       dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return;
   dt_iop_borders_params_t *p = self->params;
@@ -1013,7 +1014,7 @@ void gui_init(dt_iop_module_t *self)
   g->colorpick = gtk_color_button_new_with_rgba(&color);
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->colorpick), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->colorpick), _("select border color"));
-  g_signal_connect(G_OBJECT(g->colorpick), "color-set",
+  g_signal_connect(g->colorpick, "color-set",
                    G_CALLBACK(_colorpick_color_set), self);
   g->border_picker = dt_color_picker_new(self, DT_COLOR_PICKER_POINT, NULL);
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->border_picker),
@@ -1027,7 +1028,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->frame_colorpick), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->frame_colorpick),
                              _("select frame line color"));
-  g_signal_connect(G_OBJECT(g->frame_colorpick), "color-set",
+  g_signal_connect(g->frame_colorpick, "color-set",
                    G_CALLBACK(_frame_colorpick_color_set), self);
   g->frame_picker = dt_color_picker_new(self, DT_COLOR_PICKER_POINT, NULL);
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->frame_picker),
diff --git a/src/iop/channelmixer.c b/src/iop/channelmixer.c
index 039ed653d262..1495e8330a02 100644
--- a/src/iop/channelmixer.c
+++ b/src/iop/channelmixer.c
@@ -612,25 +612,25 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_combobox_add(g->output_channel, _("blue"));
   dt_bauhaus_combobox_add(g->output_channel, C_("channelmixer", "gray"));
   dt_bauhaus_combobox_set(g->output_channel, CHANNEL_RED);
-  g_signal_connect(G_OBJECT(g->output_channel), "value-changed", G_CALLBACK(output_callback), self);
+  g_signal_connect(g->output_channel, "value-changed", G_CALLBACK(output_callback), self);
 
   /* red */
   g->scale_red = dt_bauhaus_slider_new_with_range(self, -2.0, 2.0, 0, p->red[CHANNEL_RED], 3);
   gtk_widget_set_tooltip_text(g->scale_red, _("amount of red channel in the output channel"));
   dt_bauhaus_widget_set_label(g->scale_red, NULL, N_("red"));
-  g_signal_connect(G_OBJECT(g->scale_red), "value-changed", G_CALLBACK(red_callback), self);
+  g_signal_connect(g->scale_red, "value-changed", G_CALLBACK(red_callback), self);
 
   /* green */
   g->scale_green = dt_bauhaus_slider_new_with_range(self, -2.0, 2.0, 0, p->green[CHANNEL_RED], 3);
   gtk_widget_set_tooltip_text(g->scale_green, _("amount of green channel in the output channel"));
   dt_bauhaus_widget_set_label(g->scale_green, NULL, N_("green"));
-  g_signal_connect(G_OBJECT(g->scale_green), "value-changed", G_CALLBACK(green_callback), self);
+  g_signal_connect(g->scale_green, "value-changed", G_CALLBACK(green_callback), self);
 
   /* blue */
   g->scale_blue = dt_bauhaus_slider_new_with_range(self, -2.0, 2.0, 0, p->blue[CHANNEL_RED], 3);
   gtk_widget_set_tooltip_text(g->scale_blue, _("amount of blue channel in the output channel"));
   dt_bauhaus_widget_set_label(g->scale_blue, NULL, N_("blue"));
-  g_signal_connect(G_OBJECT(g->scale_blue), "value-changed", G_CALLBACK(blue_callback), self);
+  g_signal_connect(g->scale_blue, "value-changed", G_CALLBACK(blue_callback), self);
 
   self->widget = dt_gui_vbox(g->output_channel, g->scale_red, g->scale_green, g->scale_blue);
 }
diff --git a/src/iop/channelmixerrgb.c b/src/iop/channelmixerrgb.c
index 657cf81b3793..45b94e47ee96 100644
--- a/src/iop/channelmixerrgb.c
+++ b/src/iop/channelmixerrgb.c
@@ -2887,11 +2887,11 @@ static void _run_profile_callback(GtkWidget *widget,
   dt_dev_reprocess_preview(self->dev);
 }
 
-static void _run_validation_callback(GtkWidget *widget,
-                                    GdkEventButton *event,
-                                    dt_iop_module_t *self)
+static gboolean _run_validation_callback(GtkWidget *widget,
+                                         GdkEventButton *event,
+                                         dt_iop_module_t *self)
 {
-  if(darktable.gui->reset) return;
+  if(darktable.gui->reset) return FALSE;
   dt_iop_channelmixer_rgb_gui_data_t *g = self->gui_data;
 
   dt_iop_gui_enter_critical_section(self);
@@ -2899,6 +2899,8 @@ static void _run_validation_callback(GtkWidget *widget,
   dt_iop_gui_leave_critical_section(self);
 
   dt_dev_reprocess_preview(self->dev);
+
+  return TRUE;
 }
 
 static void _commit_profile_callback(GtkWidget *widget,
@@ -3547,7 +3549,7 @@ static gboolean _illuminant_color_draw(GtkWidget *widget,
 
 static gboolean _target_color_draw(GtkWidget *widget,
                                   cairo_t *crf,
-                                  const dt_iop_module_t *self)
+                                  dt_iop_module_t *self)
 {
   const dt_iop_channelmixer_rgb_gui_data_t *g = self->gui_data;
 
@@ -4452,7 +4454,7 @@ void gui_init(dt_iop_module_t *self)
      _("this is the color of the scene illuminant before chromatic adaptation\n"
        "this color will be turned into pure white by the adaptation."));
 
-  g_signal_connect(G_OBJECT(g->illum_color), "draw",
+  g_signal_connect(g->illum_color, "draw",
                    G_CALLBACK(_illuminant_color_draw), self);
 
   g->color_picker = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, NULL);
@@ -4478,14 +4480,14 @@ void gui_init(dt_iop_module_t *self)
     (self, 0., ILLUM_X_MAX, 0, 0, 1, 0);
   dt_bauhaus_widget_set_label(g->illum_x, NULL, N_("hue"));
   dt_bauhaus_slider_set_format(g->illum_x, "°");
-  g_signal_connect(G_OBJECT(g->illum_x), "value-changed",
+  g_signal_connect(g->illum_x, "value-changed",
                    G_CALLBACK(_illum_xy_callback), self);
 
   g->illum_y = dt_bauhaus_slider_new_with_range(self, 0., 100., 0, 0, 1);
   dt_bauhaus_widget_set_label(g->illum_y, NULL, N_("chroma"));
   dt_bauhaus_slider_set_format(g->illum_y, "%");
   dt_bauhaus_slider_set_hard_max(g->illum_y, ILLUM_Y_MAX);
-  g_signal_connect(G_OBJECT(g->illum_y), "value-changed",
+  g_signal_connect(g->illum_y, "value-changed",
                    G_CALLBACK(_illum_xy_callback), self);
 
   dt_gui_box_add(self->widget, g->illum_x, g->illum_y);
@@ -4521,7 +4523,7 @@ void gui_init(dt_iop_module_t *self)
      0, NULL, self,
      N_("correction"),
      N_("measure"));
-  g_signal_connect(G_OBJECT(g->spot_mode), "value-changed",
+  g_signal_connect(g->spot_mode, "value-changed",
                    G_CALLBACK(_spot_settings_changed_callback), self);
 
   const gchar *label = N_("take channel mixing into account");
@@ -4533,14 +4535,14 @@ void gui_init(dt_iop_module_t *self)
     (g->use_mixing,
      _("compute the target by taking the channel mixing into account.\n"
        "if disabled, only the CAT is considered."));
-  g_signal_connect(G_OBJECT(g->use_mixing), "toggled",
+  g_signal_connect(g->use_mixing, "toggled",
                    G_CALLBACK(_spot_settings_changed_callback), self);
 
   g->origin_spot = gtk_drawing_area_new();
   gtk_widget_set_vexpand(g->origin_spot, TRUE);
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->origin_spot),
                               _("the input color that should be mapped to the target"));
-  g_signal_connect(G_OBJECT(g->origin_spot), "draw",
+  g_signal_connect(g->origin_spot, "draw",
                    G_CALLBACK(_origin_color_draw), self);
 
   g->Lch_origin = gtk_label_new(_("L: \tN/A\nh: \tN/A\nc: \tN/A"));
@@ -4552,13 +4554,13 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_size_request(g->target_spot, -1, DT_PIXEL_APPLY_DPI(darktable.bauhaus->quad_width));
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->target_spot),
                               _("the desired target color after mapping"));
-  g_signal_connect(G_OBJECT(g->target_spot), "draw", G_CALLBACK(_target_color_draw), self);
+  g_signal_connect(g->target_spot, "draw", G_CALLBACK(_target_color_draw), self);
 
   g->lightness_spot = dt_bauhaus_slider_new_with_range(self, 0., LIGHTNESS_MAX, 0, 0, 1);
   dt_bauhaus_widget_set_label(g->lightness_spot, N_("mapping"), N_("lightness"));
   dt_bauhaus_slider_set_format(g->lightness_spot, "%");
   dt_bauhaus_slider_set_default(g->lightness_spot, 50.f);
-  g_signal_connect(G_OBJECT(g->lightness_spot), "value-changed",
+  g_signal_connect(g->lightness_spot, "value-changed",
                    G_CALLBACK(_spot_settings_changed_callback), self);
 
   g->hue_spot = dt_bauhaus_slider_new_with_range_and_feedback
@@ -4566,13 +4568,13 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_widget_set_label(g->hue_spot, N_("mapping"), N_("hue"));
   dt_bauhaus_slider_set_format(g->hue_spot, "°");
   dt_bauhaus_slider_set_default(g->hue_spot, 0.f);
-  g_signal_connect(G_OBJECT(g->hue_spot), "value-changed",
+  g_signal_connect(g->hue_spot, "value-changed",
                    G_CALLBACK(_spot_settings_changed_callback), self);
 
   g->chroma_spot = dt_bauhaus_slider_new_with_range(self, 0., CHROMA_MAX, 0, 0, 1);
   dt_bauhaus_widget_set_label(g->chroma_spot, N_("mapping"), N_("chroma"));
   dt_bauhaus_slider_set_default(g->chroma_spot, 0.f);
-  g_signal_connect(G_OBJECT(g->chroma_spot), "value-changed",
+  g_signal_connect(g->chroma_spot, "value-changed",
                    G_CALLBACK(_spot_settings_changed_callback), self);
 
   dt_gui_box_add(g->csspot.container,
@@ -4644,7 +4646,7 @@ void gui_init(dt_iop_module_t *self)
 
   gtk_widget_set_tooltip_text(g->cs.expander,
                               _("use a color checker target to autoset CAT and channels"));
-  g_signal_connect(G_OBJECT(g->cs.toggle), "toggled",
+  g_signal_connect(g->cs.toggle, "toggled",
                    G_CALLBACK(_start_profiling_callback), self);
 
   DT_BAUHAUS_COMBOBOX_NEW_FULL
@@ -4683,7 +4685,7 @@ void gui_init(dt_iop_module_t *self)
      _("reduce the radius of the patches to select the more or less central part.\n"
        "useful when the perspective correction is sloppy or\n"
        "the patches frame cast a shadows on the edges of the patch." ));
-  g_signal_connect(G_OBJECT(g->safety), "value-changed",
+  g_signal_connect(g->safety, "value-changed",
                    G_CALLBACK(_safety_changed_callback), self);
 
   g->label_delta_E = dt_ui_label_new("");
@@ -4693,23 +4695,23 @@ void gui_init(dt_iop_module_t *self)
   g->button_commit = dtgtk_button_new(dtgtk_cairo_paint_check_mark, 0, NULL);
   dt_action_define_iop(self, N_("calibrate"), N_("accept"),
                        g->button_commit, &dt_action_def_button);
-  g_signal_connect(G_OBJECT(g->button_commit), "button-press-event",
-                   G_CALLBACK(_commit_profile_callback), (gpointer)self);
+  g_signal_connect(g->button_commit, "button-press-event",
+                   G_CALLBACK(_commit_profile_callback), self);
   gtk_widget_set_tooltip_text(g->button_commit,
                               _("accept the computed profile and set it in the module"));
 
   g->button_profile = dtgtk_button_new(dtgtk_cairo_paint_refresh, 0, NULL);
   dt_action_define_iop(self, N_("calibrate"), N_("recompute"),
                        g->button_profile, &dt_action_def_button);
-  g_signal_connect(G_OBJECT(g->button_profile), "button-press-event",
-                   G_CALLBACK(_run_profile_callback), (gpointer)self);
+  g_signal_connect(g->button_profile, "button-press-event",
+                   G_CALLBACK(_run_profile_callback), self);
   gtk_widget_set_tooltip_text(g->button_profile, _("recompute the profile"));
 
   g->button_validate = dtgtk_button_new(dtgtk_cairo_paint_softproof, 0, NULL);
   dt_action_define_iop(self, N_("calibrate"), N_("validate"),
                        g->button_validate, &dt_action_def_button);
-  g_signal_connect(G_OBJECT(g->button_validate), "button-press-event",
-                   G_CALLBACK(_run_validation_callback), (gpointer)self);
+  g_signal_connect(g->button_validate, "button-press-event",
+                   G_CALLBACK(_run_validation_callback), self);
   gtk_widget_set_tooltip_text(g->button_validate, _("check the output delta E"));
 
   dt_gui_box_add(g->cs.container, g->checkers_list, g->optimize, g->safety,
diff --git a/src/iop/clahe.c b/src/iop/clahe.c
index 785d102415f4..a01176dc2e8b 100644
--- a/src/iop/clahe.c
+++ b/src/iop/clahe.c
@@ -326,9 +326,9 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->scale1), _("size of features to preserve"));
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->scale2), _("strength of the effect"));
 
-  g_signal_connect(G_OBJECT(g->scale1), "value-changed",
+  g_signal_connect(g->scale1, "value-changed",
                    G_CALLBACK(radius_callback), self);
-  g_signal_connect(G_OBJECT(g->scale2), "value-changed",
+  g_signal_connect(g->scale2, "value-changed",
                    G_CALLBACK(slope_callback), self);
 
   self->widget = dt_gui_vbox(g->scale1, g->scale2);
diff --git a/src/iop/clipping.c b/src/iop/clipping.c
index de5509bf205a..396c8c8dbde4 100644
--- a/src/iop/clipping.c
+++ b/src/iop/clipping.c
@@ -2105,7 +2105,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_combobox_add(g->hvflip, _("horizontal"));
   dt_bauhaus_combobox_add(g->hvflip, _("vertical"));
   dt_bauhaus_combobox_add(g->hvflip, _("both"));
-  g_signal_connect(G_OBJECT(g->hvflip), "value-changed", G_CALLBACK(hvflip_callback), self);
+  g_signal_connect(g->hvflip, "value-changed", G_CALLBACK(hvflip_callback), self);
   gtk_widget_set_tooltip_text(g->hvflip, _("mirror image horizontally and/or vertically"));
   dt_gui_box_add(self->widget, g->hvflip);
 
@@ -2121,7 +2121,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_combobox_add(g->keystone_type, _("horizontal"));
   dt_bauhaus_combobox_add(g->keystone_type, _("full"));
   gtk_widget_set_tooltip_text(g->keystone_type, _("set perspective correction for your image"));
-  g_signal_connect(G_OBJECT(g->keystone_type), "value-changed", G_CALLBACK(keystone_type_changed), self);
+  g_signal_connect(g->keystone_type, "value-changed", G_CALLBACK(keystone_type_changed), self);
   dt_gui_box_add(self->widget, g->keystone_type);
 
   g->crop_auto = dt_bauhaus_combobox_from_params(self, "crop_auto");
@@ -2236,12 +2236,12 @@ void gui_init(dt_iop_module_t *self)
 
   dt_bauhaus_combobox_set(g->aspect_presets, 0);
 
-  g_signal_connect(G_OBJECT(g->aspect_presets), "value-changed", G_CALLBACK(aspect_presets_changed), self);
+  g_signal_connect(g->aspect_presets, "value-changed", G_CALLBACK(aspect_presets_changed), self);
   gtk_widget_set_tooltip_text(g->aspect_presets, _("set the aspect ratio\n"
                                                    "the list is sorted: from most square to least square\n"
                                                    "to enter custom aspect ratio open the combobox and type ratio in x:y or decimal format"));
   dt_bauhaus_widget_set_quad_paint(g->aspect_presets, dtgtk_cairo_paint_aspectflip, 0, NULL);
-  g_signal_connect(G_OBJECT(g->aspect_presets), "quad-pressed", G_CALLBACK(aspect_flip), self);
+  g_signal_connect(g->aspect_presets, "quad-pressed", G_CALLBACK(aspect_flip), self);
   dt_gui_box_add(self->widget, g->aspect_presets);
 
   self->widget = dt_ui_notebook_page(g->notebook, _("margins"), NULL);
diff --git a/src/iop/colorbalance.c b/src/iop/colorbalance.c
index 0ca694cb4b5e..fc559de74fa7 100644
--- a/src/iop/colorbalance.c
+++ b/src/iop/colorbalance.c
@@ -1814,8 +1814,8 @@ static void _cycle_layout_callback(GtkWidget *label, GdkEventButton *event, dt_i
 #define HSL_CALLBACK(which)                                                             \
 static void which##_callback(GtkWidget *slider, dt_iop_module_t *self)                  \
 {                                                                                       \
-  dt_iop_colorbalance_params_t *p = self->params;       \
-  dt_iop_colorbalance_gui_data_t *g = self->gui_data; \
+  dt_iop_colorbalance_params_t *p = self->params;                                       \
+  dt_iop_colorbalance_gui_data_t *g = self->gui_data;                                   \
                                                                                         \
   if(darktable.gui->reset) return;                                                      \
                                                                                         \
@@ -1861,7 +1861,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_combobox_add(g->controls, _("both"));
   dt_gui_box_add(self->widget, g->controls);
   gtk_widget_set_tooltip_text(g->controls, _("color-grading mapping method"));
-  g_signal_connect(G_OBJECT(g->controls), "value-changed", G_CALLBACK(controls_callback), self);
+  g_signal_connect(g->controls, "value-changed", G_CALLBACK(controls_callback), self);
 
   const char *mode = dt_conf_get_string_const("plugins/darkroom/colorbalance/controls");
   dt_bauhaus_combobox_set(g->controls, !g_strcmp0(mode, "RGBL") ? RGBL :
@@ -1898,7 +1898,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->main_label, _("click to cycle layout"));
   GtkWidget *main_label_box = gtk_event_box_new();
   gtk_container_add(GTK_CONTAINER(main_label_box), g->main_label);
-  g_signal_connect(G_OBJECT(main_label_box), "button-release-event", G_CALLBACK(_cycle_layout_callback), self);
+  g_signal_connect(main_label_box, "button-release-event", G_CALLBACK(_cycle_layout_callback), self);
 
   g->main_box = gtk_event_box_new(); // is filled in _configure_slider_blocks
 
@@ -1944,7 +1944,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_stop(g->hue_##which, 0.830f, 1.0f, 0.0f, 1.0f);     \
   dt_bauhaus_slider_set_stop(g->hue_##which, 1.0f,   1.0f, 0.0f, 0.0f);     \
   gtk_widget_set_tooltip_text(g->hue_##which, _("select the hue"));         \
-  g_signal_connect(G_OBJECT(g->hue_##which), "value-changed",               \
+  g_signal_connect(g->hue_##which, "value-changed",                         \
                    G_CALLBACK(which##_callback), self);                     \
                                                                             \
   g->sat_##which = dt_bauhaus_slider_new_with_range_and_feedback(self,      \
@@ -1955,7 +1955,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_stop(g->sat_##which, 0.0f, 0.2f, 0.2f, 0.2f);       \
   dt_bauhaus_slider_set_stop(g->sat_##which, 1.0f, 1.0f, 1.0f, 1.0f);       \
   gtk_widget_set_tooltip_text(g->sat_##which, _("select the saturation"));  \
-  g_signal_connect(G_OBJECT(g->sat_##which), "value-changed",               \
+  g_signal_connect(g->sat_##which, "value-changed",                         \
                    G_CALLBACK(which##_callback), self);                     \
                                                                             \
   dt_gui_box_add(self->widget, g->hue_##which, g->sat_##which);             \
diff --git a/src/iop/colorbalancergb.c b/src/iop/colorbalancergb.c
index 13cf1f84b922..5645d57842bf 100644
--- a/src/iop/colorbalancergb.c
+++ b/src/iop/colorbalancergb.c
@@ -1972,7 +1972,7 @@ void gui_init(dt_iop_module_t *self)
                                                "plugins/darkroom/colorbalancergb/graphheight"));
   g_object_set_data(G_OBJECT(g->area), "iop-instance", self);
   dt_action_define_iop(self, NULL, N_("graph"), GTK_WIDGET(g->area), NULL);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
   dt_gui_box_add(self->widget, GTK_WIDGET(g->area));
 
   g->shadows_weight = dt_bauhaus_slider_from_params(self, "shadows_weight");
@@ -2011,17 +2011,17 @@ void gui_init(dt_iop_module_t *self)
   g->checker_color_1_picker = gtk_color_button_new();
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->checker_color_1_picker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->checker_color_1_picker), _("select color of the checkerboard from a swatch"));
-  g_signal_connect(G_OBJECT(g->checker_color_1_picker), "color-set", G_CALLBACK(checker_1_picker_callback), self);
+  g_signal_connect(g->checker_color_1_picker, "color-set", G_CALLBACK(checker_1_picker_callback), self);
 
   g->checker_color_2_picker = gtk_color_button_new();
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->checker_color_2_picker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->checker_color_2_picker), _("select color of the checkerboard from a swatch"));
-  g_signal_connect(G_OBJECT(g->checker_color_2_picker), "color-set", G_CALLBACK(checker_2_picker_callback), self);
+  g_signal_connect(g->checker_color_2_picker, "color-set", G_CALLBACK(checker_2_picker_callback), self);
 
   g->checker_size = dt_bauhaus_slider_new_with_range(self, 2., 32., 0, 8., 0);
   dt_bauhaus_slider_set_format(g->checker_size, _(" px"));
   dt_bauhaus_widget_set_label(g->checker_size,  NULL, _("checkerboard size"));
-  g_signal_connect(G_OBJECT(g->checker_size), "value-changed", G_CALLBACK(checker_size_callback), self);
+  g_signal_connect(g->checker_size, "value-changed", G_CALLBACK(checker_size_callback), self);
 
   dt_gui_box_add(self->widget,
     dt_gui_hbox(dt_gui_expand(dt_ui_label_new(_("checkerboard color 1"))), g->checker_color_1_picker),
diff --git a/src/iop/colorchecker.c b/src/iop/colorchecker.c
index 41e0b5237e34..ce5ae6b54c39 100644
--- a/src/iop/colorchecker.c
+++ b/src/iop/colorchecker.c
@@ -1537,11 +1537,11 @@ void gui_init(dt_iop_module_t *self)
                         GDK_POINTER_MOTION_MASK
                         | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                         | GDK_LEAVE_NOTIFY_MASK);
-  g_signal_connect(G_OBJECT(g->area), "draw",
+  g_signal_connect(g->area, "draw",
                    G_CALLBACK(checker_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(checker_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(checker_motion_notify), self);
 
   g->patch = 0;
@@ -1615,17 +1615,17 @@ void gui_init(dt_iop_module_t *self)
   self->widget = dt_gui_vbox(g->area, g->combobox_patch, g->scale_L, g->scale_a,
                                       g->scale_b, g->scale_C, g->combobox_target);
 
-  g_signal_connect(G_OBJECT(g->combobox_patch), "value-changed",
+  g_signal_connect(g->combobox_patch, "value-changed",
                    G_CALLBACK(patch_callback), self);
-  g_signal_connect(G_OBJECT(g->scale_L), "value-changed",
+  g_signal_connect(g->scale_L, "value-changed",
                    G_CALLBACK(target_L_callback), self);
-  g_signal_connect(G_OBJECT(g->scale_a), "value-changed",
+  g_signal_connect(g->scale_a, "value-changed",
                    G_CALLBACK(target_a_callback), self);
-  g_signal_connect(G_OBJECT(g->scale_b), "value-changed",
+  g_signal_connect(g->scale_b, "value-changed",
                    G_CALLBACK(target_b_callback), self);
-  g_signal_connect(G_OBJECT(g->scale_C), "value-changed",
+  g_signal_connect(g->scale_C, "value-changed",
                    G_CALLBACK(target_C_callback), self);
-  g_signal_connect(G_OBJECT(g->combobox_target), "value-changed",
+  g_signal_connect(g->combobox_target, "value-changed",
                    G_CALLBACK(target_callback), self);
 }
 
diff --git a/src/iop/colorcorrection.c b/src/iop/colorcorrection.c
index 8a7551e3c5b4..687236deb5b8 100644
--- a/src/iop/colorcorrection.c
+++ b/src/iop/colorcorrection.c
@@ -246,15 +246,15 @@ void gui_init(dt_iop_module_t *self)
                                            | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                            | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_colorcorrection_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(dt_iop_colorcorrection_button_press),
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_colorcorrection_draw), self);
+  g_signal_connect(g->area, "button-press-event", G_CALLBACK(dt_iop_colorcorrection_button_press),
                    self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(dt_iop_colorcorrection_motion_notify),
+  g_signal_connect(g->area, "motion-notify-event", G_CALLBACK(dt_iop_colorcorrection_motion_notify),
                    self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(dt_iop_colorcorrection_leave_notify),
+  g_signal_connect(g->area, "leave-notify-event", G_CALLBACK(dt_iop_colorcorrection_leave_notify),
                    self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event", G_CALLBACK(dt_iop_colorcorrection_scrolled), self);
-  g_signal_connect(G_OBJECT(g->area), "key-press-event", G_CALLBACK(dt_iop_colorcorrection_key_press), self);
+  g_signal_connect(g->area, "scroll-event", G_CALLBACK(dt_iop_colorcorrection_scrolled), self);
+  g_signal_connect(g->area, "key-press-event", G_CALLBACK(dt_iop_colorcorrection_key_press), self);
 
   self->widget = dt_gui_vbox(g->area);
   g->slider = dt_bauhaus_slider_from_params(self, N_("saturation"));
diff --git a/src/iop/colorequal.c b/src/iop/colorequal.c
index eb44791463e4..cbf2362fa341 100644
--- a/src/iop/colorequal.c
+++ b/src/iop/colorequal.c
@@ -3005,7 +3005,7 @@ void gui_init(dt_iop_module_t *self)
   static dt_action_def_t notebook_def = { };
   g->notebook = dt_ui_notebook_new(&notebook_def);
   dt_action_define_iop(self, NULL, N_("page"), GTK_WIDGET(g->notebook), &notebook_def);
-  g_signal_connect(G_OBJECT(g->notebook), "switch_page",
+  g_signal_connect(g->notebook, "switch-page",
                    G_CALLBACK(_channel_tabs_switch_callback), self);
 
   // graph
@@ -3024,16 +3024,16 @@ void gui_init(dt_iop_module_t *self)
                         | GDK_BUTTON_RELEASE_MASK
                         | GDK_SCROLL_MASK
                         | GDK_SMOOTH_SCROLL_MASK);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(_iop_colorequalizer_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "draw", G_CALLBACK(_iop_colorequalizer_draw), self);
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(_area_button_press_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event",
+  g_signal_connect(g->area, "button-release-event",
                    G_CALLBACK(_area_button_release_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(_area_motion_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(_area_scrolled_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "size_allocate",
+  g_signal_connect(g->area, "size-allocate",
                    G_CALLBACK(_area_size_callback), self);
 
   GtkWidget *box = self->widget = dt_gui_vbox(g->notebook, g->area);
diff --git a/src/iop/colorin.c b/src/iop/colorin.c
index daefabb704de..9f67f0d771f7 100644
--- a/src/iop/colorin.c
+++ b/src/iop/colorin.c
@@ -2052,10 +2052,10 @@ void gui_init(dt_iop_module_t *self)
     g_free(tooltip);
   }
 
-  g_signal_connect(G_OBJECT(g->profile_combobox), "value-changed",
-                   G_CALLBACK(_profile_changed), (gpointer)self);
-  g_signal_connect(G_OBJECT(g->work_combobox), "value-changed",
-                   G_CALLBACK(_workicc_changed), (gpointer)self);
+  g_signal_connect(g->profile_combobox, "value-changed",
+                   G_CALLBACK(_profile_changed), self);
+  g_signal_connect(g->work_combobox, "value-changed",
+                   G_CALLBACK(_workicc_changed), self);
 
   g->clipping_combobox = dt_bauhaus_combobox_from_params(self, "normalize");
   gtk_widget_set_tooltip_text(g->clipping_combobox,
diff --git a/src/iop/colormapping.c b/src/iop/colormapping.c
index 3a9f2ed2b06e..cc0a264c5a1a 100644
--- a/src/iop/colormapping.c
+++ b/src/iop/colormapping.c
@@ -992,10 +992,10 @@ void gui_init(dt_iop_module_t *self)
   g->buffer = NULL;
 
   g->source_area = dtgtk_drawing_area_new_with_aspect_ratio(1.0 / 3.0);
-  g_signal_connect(G_OBJECT(g->source_area), "draw", G_CALLBACK(cluster_preview_draw), self);
+  g_signal_connect(g->source_area, "draw", G_CALLBACK(cluster_preview_draw), self);
 
   g->target_area = dtgtk_drawing_area_new_with_aspect_ratio(1.0 / 3.0);
-  g_signal_connect(G_OBJECT(g->target_area), "draw", G_CALLBACK(cluster_preview_draw), self);
+  g_signal_connect(g->target_area, "draw", G_CALLBACK(cluster_preview_draw), self);
 
   GtkWidget *box = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 5);
 
diff --git a/src/iop/colorout.c b/src/iop/colorout.c
index 9ba89ed74c0d..b6f331e5abb6 100644
--- a/src/iop/colorout.c
+++ b/src/iop/colorout.c
@@ -862,7 +862,7 @@ void gui_init(dt_iop_module_t *self)
 
   self->widget = dt_gui_vbox(g->output_intent, g->output_profile);
 
-  g_signal_connect(G_OBJECT(g->output_profile), "value-changed",
+  g_signal_connect(g->output_profile, "value-changed",
                    G_CALLBACK(output_profile_changed), (gpointer)self);
 
   // reload the profiles when the display or softproof profile changed!
diff --git a/src/iop/colorzones.c b/src/iop/colorzones.c
index e79d373e56a5..bd3d074da6d5 100644
--- a/src/iop/colorzones.c
+++ b/src/iop/colorzones.c
@@ -2628,7 +2628,7 @@ void gui_init(dt_iop_module_t *self)
 
   gtk_widget_show(gtk_notebook_get_nth_page(g->channel_tabs, g->channel));
   gtk_notebook_set_current_page(g->channel_tabs, g->channel);
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page",
+  g_signal_connect(g->channel_tabs, "switch-page",
                    G_CALLBACK(_channel_tabs_switch_callback), self);
 
   // color pickers
@@ -2674,14 +2674,14 @@ void gui_init(dt_iop_module_t *self)
                           PANGO_ELLIPSIZE_START);
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->chk_edit_by_area), g->edit_by_area);
   gtk_widget_set_tooltip_text(g->chk_edit_by_area, _("edit the curve nodes by area"));
-  g_signal_connect(G_OBJECT(g->chk_edit_by_area), "toggled",
+  g_signal_connect(g->chk_edit_by_area, "toggled",
                    G_CALLBACK(_edit_by_area_callback), self);
 
   // display selection
   g->bt_showmask = dtgtk_togglebutton_new(dtgtk_cairo_paint_showmask, 0, NULL);
   dt_gui_add_class(g->bt_showmask, "dt_transparent_background");
   gtk_widget_set_tooltip_text(g->bt_showmask, _("display selection"));
-  g_signal_connect(G_OBJECT(g->bt_showmask), "toggled",
+  g_signal_connect(g->bt_showmask, "toggled",
                    G_CALLBACK(_display_mask_callback), self);
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->bt_showmask), FALSE);
 
@@ -2707,25 +2707,25 @@ void gui_init(dt_iop_module_t *self)
   g_object_set_data(G_OBJECT(g->area), "iop-instance", self);
   dt_action_define_iop(self, NULL, N_("graph"), GTK_WIDGET(g->area), &_action_def_zones);
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw",
+  g_signal_connect(g->area, "draw",
                    G_CALLBACK(_area_draw_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(_area_button_press_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event",
+  g_signal_connect(g->area, "button-release-event",
                    G_CALLBACK(_area_button_release_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(_area_motion_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(g->area, "leave-notify-event",
                    G_CALLBACK(_area_leave_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(_area_scrolled_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "key-press-event",
+  g_signal_connect(g->area, "key-press-event",
                    G_CALLBACK(_area_key_press_callback), self);
 
   gtk_widget_add_events(GTK_WIDGET(g->bottom_area), GDK_BUTTON_PRESS_MASK);
-  g_signal_connect(G_OBJECT(g->bottom_area), "draw",
+  g_signal_connect(g->bottom_area, "draw",
                    G_CALLBACK(_bottom_area_draw_callback), self);
-  g_signal_connect(G_OBJECT(g->bottom_area), "button-press-event",
+  g_signal_connect(g->bottom_area, "button-press-event",
                    G_CALLBACK(_bottom_area_button_press_callback),
                    self);
 
@@ -2736,7 +2736,7 @@ void gui_init(dt_iop_module_t *self)
         "- cubic spline is better to produce smooth curves but oscillates when nodes are too close\n"
         "- centripetal is better to avoids cusps and oscillations with close nodes but is less smooth\n"
         "- monotonic is better for accuracy of pure analytical functions (log, gamma, exp)"));
-  g_signal_connect(G_OBJECT(g->interpolator), "value-changed",
+  g_signal_connect(g->interpolator, "value-changed",
                    G_CALLBACK(_interpolator_callback), self);
 }
 
diff --git a/src/iop/crop.c b/src/iop/crop.c
index 4b90763e7712..c29bf1c32f41 100644
--- a/src/iop/crop.c
+++ b/src/iop/crop.c
@@ -1269,7 +1269,7 @@ void gui_init(dt_iop_module_t *self)
 
   dt_bauhaus_combobox_set(g->aspect_presets, 0);
 
-  g_signal_connect(G_OBJECT(g->aspect_presets), "value-changed",
+  g_signal_connect(g->aspect_presets, "value-changed",
                    G_CALLBACK(_event_aspect_presets_changed), self);
   gtk_widget_set_tooltip_text
     (g->aspect_presets,
diff --git a/src/iop/denoiseprofile.c b/src/iop/denoiseprofile.c
index 1f57e36269e7..7ce956ff04c5 100644
--- a/src/iop/denoiseprofile.c
+++ b/src/iop/denoiseprofile.c
@@ -3774,13 +3774,13 @@ void gui_init(dt_iop_module_t *self)
   dt_ui_notebook_page(g->channel_tabs, N_("R"), NULL);
   dt_ui_notebook_page(g->channel_tabs, N_("G"), NULL);
   dt_ui_notebook_page(g->channel_tabs, N_("B"), NULL);
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page",
+  g_signal_connect(g->channel_tabs, "switch-page",
                    G_CALLBACK(denoiseprofile_tab_switch), self);
 
   g->channel_tabs_Y0U0V0 = GTK_NOTEBOOK(gtk_notebook_new());
   dt_ui_notebook_page(g->channel_tabs_Y0U0V0, N_("Y0"), NULL);
   dt_ui_notebook_page(g->channel_tabs_Y0U0V0, N_("U0V0"), NULL);
-  g_signal_connect(G_OBJECT(g->channel_tabs_Y0U0V0), "switch_page",
+  g_signal_connect(g->channel_tabs_Y0U0V0, "switch-page",
                    G_CALLBACK(denoiseprofile_tab_switch), self);
 
   const int ch = (int)g->channel;
@@ -3802,16 +3802,16 @@ void gui_init(dt_iop_module_t *self)
                                                "plugins/darkroom/denoiseprofile/graphheight"));
   dt_action_define_iop(self, NULL, N_("graph"), GTK_WIDGET(g->area), NULL);
 
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(denoiseprofile_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(GTK_WIDGET(g->area), "draw", G_CALLBACK(denoiseprofile_draw), self);
+  g_signal_connect(GTK_WIDGET(g->area), "button-press-event",
                    G_CALLBACK(denoiseprofile_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event",
+  g_signal_connect(GTK_WIDGET(g->area), "button-release-event",
                    G_CALLBACK(denoiseprofile_button_release), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(GTK_WIDGET(g->area), "motion-notify-event",
                    G_CALLBACK(denoiseprofile_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(GTK_WIDGET(g->area), "leave-notify-event",
                    G_CALLBACK(denoiseprofile_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(GTK_WIDGET(g->area), "scroll-event",
                    G_CALLBACK(denoiseprofile_scrolled), self);
 
   dt_gui_box_add(g->box_wavelets, g->channel_tabs, g->channel_tabs_Y0U0V0, g->area);
@@ -3839,14 +3839,14 @@ void gui_init(dt_iop_module_t *self)
                                 dt_gui_hbox(dt_ui_label_new(_("variance green: ")), g->label_var_G),
                                 dt_gui_hbox(dt_ui_label_new(_("variance blue: ")), g->label_var_B));
 
-  g_signal_connect(G_OBJECT(g->box_variance), "draw",
+  g_signal_connect(g->box_variance, "draw",
                    G_CALLBACK(denoiseprofile_draw_variance), self);
 
   // start building top level widget
 
   g->profile = dt_bauhaus_combobox_new(self);
   dt_bauhaus_widget_set_label(g->profile, NULL, N_("profile"));
-  g_signal_connect(G_OBJECT(g->profile), "value-changed",
+  g_signal_connect(g->profile, "value-changed",
                    G_CALLBACK(profile_callback), self);
   self->widget = dt_gui_vbox(g->profile);
 
diff --git a/src/iop/exposure.c b/src/iop/exposure.c
index 2b23da4dd2a1..d55a5a477e8c 100644
--- a/src/iop/exposure.c
+++ b/src/iop/exposure.c
@@ -1295,7 +1295,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->origin_spot),
                               _("the input color that should be mapped to the target"));
 
-  g_signal_connect(G_OBJECT(g->origin_spot), "draw", G_CALLBACK(_origin_color_draw), self);
+  g_signal_connect(g->origin_spot, "draw", G_CALLBACK(_origin_color_draw), self);
 
   g->Lch_origin = gtk_label_new(_("L : \tN/A"));
   gtk_widget_set_tooltip_text
@@ -1309,12 +1309,12 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->target_spot),
                               _("the desired target exposure after mapping"));
 
-  g_signal_connect(G_OBJECT(g->target_spot), "draw", G_CALLBACK(_target_color_draw), self);
+  g_signal_connect(g->target_spot, "draw", G_CALLBACK(_target_color_draw), self);
 
   g->lightness_spot = dt_bauhaus_slider_new_with_range(self, 0., 100., 0, 50.f, 1);
   dt_bauhaus_widget_set_label(g->lightness_spot, NULL, N_("lightness"));
   dt_bauhaus_slider_set_format(g->lightness_spot, "%");
-  g_signal_connect(G_OBJECT(g->lightness_spot), "value-changed",
+  g_signal_connect(g->lightness_spot, "value-changed",
                    G_CALLBACK(_spot_settings_changed_callback), self);
 
   dt_gui_box_add(g->cs.container,
diff --git a/src/iop/filmic.c b/src/iop/filmic.c
index 02209487aedb..3e820f191a8b 100644
--- a/src/iop/filmic.c
+++ b/src/iop/filmic.c
@@ -1459,7 +1459,7 @@ void gui_init(dt_iop_module_t *self)
   // don't make the area square to safe some vertical space -- it's not interactive anyway
   g->area = GTK_DRAWING_AREA(dtgtk_drawing_area_new_with_aspect_ratio(0.618));
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->area), _("read-only graph, use the parameters below to set the nodes"));
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
 
   // grey_point_source slider
   g->grey_point_source = dt_bauhaus_slider_new_with_range(self, 0.0, 100., 0, p->grey_point_source, 2);
@@ -1468,7 +1468,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->grey_point_source, "%");
   gtk_widget_set_tooltip_text(g->grey_point_source, _("adjust to match the average luminance of the subject.\n"
                                                       "except in back-lighting situations, this should be around 18%."));
-  g_signal_connect(G_OBJECT(g->grey_point_source), "value-changed", G_CALLBACK(grey_point_source_callback), self);
+  g_signal_connect(g->grey_point_source, "value-changed", G_CALLBACK(grey_point_source_callback), self);
   dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE,
                       g->grey_point_source);
 
@@ -1480,7 +1480,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->white_point_source, _("number of stops between middle gray and pure white.\n"
                                                        "this is a reading a lightmeter would give you on the scene.\n"
                                                        "adjust so highlights clipping is avoided"));
-  g_signal_connect(G_OBJECT(g->white_point_source), "value-changed", G_CALLBACK(white_point_source_callback), self);
+  g_signal_connect(g->white_point_source, "value-changed", G_CALLBACK(white_point_source_callback), self);
   dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE,
                       g->white_point_source);
 
@@ -1492,7 +1492,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->black_point_source, _("number of stops between middle gray and pure black.\n"
                                                        "this is a reading a lightmeter would give you on the scene.\n"
                                                        "increase to get more contrast.\ndecrease to recover more details in low-lights."));
-  g_signal_connect(G_OBJECT(g->black_point_source), "value-changed", G_CALLBACK(black_point_source_callback), self);
+  g_signal_connect(g->black_point_source, "value-changed", G_CALLBACK(black_point_source_callback), self);
   dt_color_picker_new(self, DT_COLOR_PICKER_AREA | DT_COLOR_PICKER_DENOISE,
                       g->black_point_source);
 
@@ -1502,7 +1502,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->security_factor, "%");
   gtk_widget_set_tooltip_text(g->security_factor, _("increase or decrease the computed dynamic range.\n"
                                                     "useful in conjunction with \"auto tune levels\"."));
-  g_signal_connect(G_OBJECT(g->security_factor), "value-changed", G_CALLBACK(security_threshold_callback), self);
+  g_signal_connect(g->security_factor, "value-changed", G_CALLBACK(security_threshold_callback), self);
 
   // Auto tune slider
   g->auto_button = dt_bauhaus_combobox_new(self);
@@ -1519,7 +1519,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_widget_set_label(g->contrast, NULL, N_("contrast"));
   gtk_widget_set_tooltip_text(g->contrast, _("slope of the linear part of the curve\n"
                                              "affects mostly the mid-tones"));
-  g_signal_connect(G_OBJECT(g->contrast), "value-changed", G_CALLBACK(contrast_callback), self);
+  g_signal_connect(g->contrast, "value-changed", G_CALLBACK(contrast_callback), self);
 
   // latitude slider
   g->latitude_stops = dt_bauhaus_slider_new_with_range(self, 0.01, 16.0, 0, p->latitude_stops, 3);
@@ -1529,7 +1529,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->latitude_stops, _("width of the linear domain in the middle of the curve.\n"
                                                    "increase to get more contrast at the extreme luminances.\n"
                                                    "this has no effect on mid-tones."));
-  g_signal_connect(G_OBJECT(g->latitude_stops), "value-changed", G_CALLBACK(latitude_stops_callback), self);
+  g_signal_connect(g->latitude_stops, "value-changed", G_CALLBACK(latitude_stops_callback), self);
 
   // balance slider
   g->balance = dt_bauhaus_slider_new_with_range(self, -50., 50., 0, p->balance, 2);
@@ -1537,7 +1537,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->balance, "%");
   gtk_widget_set_tooltip_text(g->balance, _("slides the latitude along the slope\nto give more room to shadows or highlights.\n"
                                             "use it if you need to protect the details\nat one extremity of the histogram."));
-  g_signal_connect(G_OBJECT(g->balance), "value-changed", G_CALLBACK(balance_callback), self);
+  g_signal_connect(g->balance, "value-changed", G_CALLBACK(balance_callback), self);
 
   // saturation slider
   g->global_saturation = dt_bauhaus_slider_new_with_range(self, 0., 1000., 0, p->global_saturation, 2);
@@ -1546,7 +1546,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->global_saturation, "%");
   gtk_widget_set_tooltip_text(g->global_saturation, _("desaturates the input of the module globally.\n"
                                                       "you need to set this value below 100%\nif the chrominance preservation is enabled."));
-  g_signal_connect(G_OBJECT(g->global_saturation), "value-changed", G_CALLBACK(global_saturation_callback), self);
+  g_signal_connect(g->global_saturation, "value-changed", G_CALLBACK(global_saturation_callback), self);
 
   // saturation slider
   g->saturation = dt_bauhaus_slider_new_with_range(self, 0., 1000., 0, (powf(10.0f, p->saturation/100.0f) - 1.0f) / 9.0f *100.0f, 2);
@@ -1555,7 +1555,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->saturation, "%");
   gtk_widget_set_tooltip_text(g->saturation, _("desaturates the output of the module\nspecifically at extreme luminances.\n"
                                                "decrease if shadows and/or highlights are over-saturated."));
-  g_signal_connect(G_OBJECT(g->saturation), "value-changed", G_CALLBACK(saturation_callback), self);
+  g_signal_connect(g->saturation, "value-changed", G_CALLBACK(saturation_callback), self);
 
     /* From src/common/curve_tools.h :
     #define CUBIC_SPLINE 0
@@ -1569,7 +1569,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_combobox_add(g->interpolator, _("linear")); // monotonic spline
   dt_bauhaus_combobox_add(g->interpolator, _("optimized")); // monotonic spline
   gtk_widget_set_tooltip_text(g->interpolator, _("change this method if you see reversed contrast or faded blacks"));
-  g_signal_connect(G_OBJECT(g->interpolator), "value-changed", G_CALLBACK(interpolator_callback), self);
+  g_signal_connect(g->interpolator, "value-changed", G_CALLBACK(interpolator_callback), self);
 
   // Preserve color
   g->preserve_color = gtk_check_button_new_with_label(_("preserve the chrominance"));
@@ -1577,7 +1577,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->preserve_color, _("ensure the original color are preserved.\n"
                                                    "may reinforce chromatic aberrations.\n"
                                                    "you need to manually tune the saturation when using this mode."));
-  g_signal_connect(G_OBJECT(g->preserve_color), "toggled", G_CALLBACK(preserve_color_callback), self);
+  g_signal_connect(g->preserve_color, "toggled", G_CALLBACK(preserve_color_callback), self);
 
   // Black slider
   g->black_point_target = dt_bauhaus_slider_new_with_range(self, 0.0, 100.0, 0, p->black_point_target, 2);
@@ -1585,7 +1585,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->black_point_target, "%");
   gtk_widget_set_tooltip_text(g->black_point_target, _("luminance of output pure black, "
                                                         "this should be 0%\nexcept if you want a faded look"));
-  g_signal_connect(G_OBJECT(g->black_point_target), "value-changed", G_CALLBACK(black_point_target_callback), self);
+  g_signal_connect(g->black_point_target, "value-changed", G_CALLBACK(black_point_target_callback), self);
 
   // grey_point_source slider
   g->grey_point_target = dt_bauhaus_slider_new_with_range(self, 0.1, 50., 0, p->grey_point_target, 2);
@@ -1593,7 +1593,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->grey_point_target, "%");
   gtk_widget_set_tooltip_text(g->grey_point_target, _("middle gray value of the target display or color space.\n"
                                                       "you should never touch that unless you know what you are doing."));
-  g_signal_connect(G_OBJECT(g->grey_point_target), "value-changed", G_CALLBACK(grey_point_target_callback), self);
+  g_signal_connect(g->grey_point_target, "value-changed", G_CALLBACK(grey_point_target_callback), self);
 
   // White slider
   g->white_point_target = dt_bauhaus_slider_new_with_range(self, 0.0, 100.0, 0, p->white_point_target, 2);
@@ -1601,18 +1601,18 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->white_point_target, "%");
   gtk_widget_set_tooltip_text(g->white_point_target, _("luminance of output pure white, "
                                                         "this should be 100%\nexcept if you want a faded look"));
-  g_signal_connect(G_OBJECT(g->white_point_target), "value-changed", G_CALLBACK(white_point_target_callback), self);
+  g_signal_connect(g->white_point_target, "value-changed", G_CALLBACK(white_point_target_callback), self);
 
   // power/gamma slider
   g->output_power = dt_bauhaus_slider_new_with_range(self, 1.0, 2.4, 0, p->output_power, 2);
   dt_bauhaus_widget_set_label(g->output_power, NULL, N_("target gamma"));
   gtk_widget_set_tooltip_text(g->output_power, _("power or gamma of the transfer function\nof the display or color space.\n"
                                                  "you should never touch that unless you know what you are doing."));
-  g_signal_connect(G_OBJECT(g->output_power), "value-changed", G_CALLBACK(output_power_callback), self);
+  g_signal_connect(g->output_power, "value-changed", G_CALLBACK(output_power_callback), self);
 
   // add collapsible section for those extra options that are generally not to be used
   g->extra_toggle = dtgtk_togglebutton_new(dtgtk_cairo_paint_solid_arrow, CPF_DIRECTION_LEFT, NULL);
-  g_signal_connect(G_OBJECT(g->extra_toggle), "toggled", G_CALLBACK(_extra_options_button_changed),  (gpointer)self);
+  g_signal_connect(g->extra_toggle, "toggled", G_CALLBACK(_extra_options_button_changed),  (gpointer)self);
   g->extra_expander = dtgtk_expander_new(dt_gui_hbox(dt_ui_section_label_new(C_("section", "destination/display")), 
                                                      g->extra_toggle), 
                                          dt_gui_vbox(g->black_point_target,
diff --git a/src/iop/filmicrgb.c b/src/iop/filmicrgb.c
index e8d2d75dc2a1..4a277d7031d3 100644
--- a/src/iop/filmicrgb.c
+++ b/src/iop/filmicrgb.c
@@ -4367,11 +4367,11 @@ void gui_init(dt_iop_module_t *self)
   dt_action_define_iop(self, NULL, N_("graph"), GTK_WIDGET(g->area), NULL);
 
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(area_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(area_enter_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "enter-notify-event", G_CALLBACK(area_enter_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(area_motion_notify), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
+  g_signal_connect(g->area, "button-press-event", G_CALLBACK(area_button_press), self);
+  g_signal_connect(g->area, "leave-notify-event", G_CALLBACK(area_enter_leave_notify), self);
+  g_signal_connect(g->area, "enter-notify-event", G_CALLBACK(area_enter_leave_notify), self);
+  g_signal_connect(g->area, "motion-notify-event", G_CALLBACK(area_motion_notify), self);
 
   // Init GTK notebook
   static struct dt_action_def_t notebook_def = { };
diff --git a/src/iop/hotpixels.c b/src/iop/hotpixels.c
index fe03fe784ab9..d3577dfdbafc 100644
--- a/src/iop/hotpixels.c
+++ b/src/iop/hotpixels.c
@@ -437,7 +437,7 @@ void gui_init(dt_iop_module_t *self)
   g->pixels_fixed = -1;
 
   GtkWidget *box_raw = self->widget = dt_gui_vbox();
-  g_signal_connect(G_OBJECT(box_raw), "draw", G_CALLBACK(draw), self);
+  g_signal_connect(box_raw, "draw", G_CALLBACK(draw), self);
 
   g->threshold = dt_bauhaus_slider_from_params(self, N_("threshold"));
   dt_bauhaus_slider_set_digits(g->threshold, 4);
diff --git a/src/iop/invert.c b/src/iop/invert.c
index b22ca1ae7d4f..cccb6c06d56b 100644
--- a/src/iop/invert.c
+++ b/src/iop/invert.c
@@ -493,7 +493,7 @@ void gui_init(dt_iop_module_t *self)
   dt_action_define(DT_ACTION(self), NULL, N_("pick color of film material from image"), g->colorpicker, &dt_action_def_button);
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->colorpicker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->colorpicker), _("select color of film material"));
-  g_signal_connect(G_OBJECT(g->colorpicker), "color-set", G_CALLBACK(colorpicker_callback), self);
+  g_signal_connect(g->colorpicker, "color-set", G_CALLBACK(colorpicker_callback), self);
 
   g->picker = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, NULL);
 
diff --git a/src/iop/lens.cc b/src/iop/lens.cc
index 343bf69ca288..f8c220d4f04f 100644
--- a/src/iop/lens.cc
+++ b/src/iop/lens.cc
@@ -3815,7 +3815,7 @@ static GtkMenu *camera_menu_fill(dt_iop_module_t *self,
     }
     gtk_widget_show(item);
     g_object_set_data(G_OBJECT(item), "lfCamera", (void *)camlist[i]);
-    g_signal_connect(G_OBJECT(item), "activate",
+    g_signal_connect(item, "activate",
                      G_CALLBACK(_camera_menu_select), self);
     gtk_menu_shell_append(GTK_MENU_SHELL(submenu), item);
   }
@@ -4145,7 +4145,7 @@ static GtkMenu *_lens_menu_fill(dt_iop_module_t *self,
     item = gtk_menu_item_new_with_label(lf_mlstr_get(lenslist[i]->Model));
     gtk_widget_show(item);
     g_object_set_data(G_OBJECT(item), "lfLens", (void *)lenslist[i]);
-    g_signal_connect(G_OBJECT(item), "activate",
+    g_signal_connect(item, "activate",
                      G_CALLBACK(_lens_menu_select), self);
     gtk_menu_shell_append(GTK_MENU_SHELL(submenu), item);
   }
@@ -4408,21 +4408,21 @@ void gui_init(dt_iop_module_t *self)
   g->focal_length = dt_gui_expand(dt_bauhaus_combobox_new(self));
   dt_bauhaus_widget_set_label(g->focal_length, NULL, N_("focal length"));
   gtk_widget_set_tooltip_text(g->focal_length, _("focal length (mm)"));
-  g_signal_connect(G_OBJECT(g->focal_length), "value-changed",
+  g_signal_connect(g->focal_length, "value-changed",
                    G_CALLBACK(_lens_comboentry_focal_update), self);
   dt_bauhaus_combobox_set_editable(g->focal_length, 1);
 
   g->aperture = dt_gui_expand(dt_bauhaus_combobox_new(self));
   dt_bauhaus_widget_set_label(g->aperture, NULL, N_("aperture"));
   gtk_widget_set_tooltip_text(g->aperture, _("f-number (aperture)"));
-  g_signal_connect(G_OBJECT(g->aperture), "value-changed",
+  g_signal_connect(g->aperture, "value-changed",
                    G_CALLBACK(_lens_comboentry_aperture_update), self);
   dt_bauhaus_combobox_set_editable(g->aperture, 1);
 
   g->distance = dt_gui_expand(dt_bauhaus_combobox_new(self));
   dt_bauhaus_widget_set_label(g->distance, NULL, N_("distance"));
   gtk_widget_set_tooltip_text(g->distance, _("distance to subject"));
-  g_signal_connect(G_OBJECT(g->distance), "value-changed",
+  g_signal_connect(g->distance, "value-changed",
                    G_CALLBACK(_lens_comboentry_distance_update), self);
   dt_bauhaus_combobox_set_editable(g->distance, 1);
 
@@ -4492,7 +4492,7 @@ void gui_init(dt_iop_module_t *self)
        "once enabled, you won't be able to\n"
        "return back to old algorithm."));
   GtkWidget *box_md = dt_gui_vbox(g->use_latest_md_algo);
-  g_signal_connect(G_OBJECT(g->use_latest_md_algo), "toggled",
+  g_signal_connect(g->use_latest_md_algo, "toggled",
                    G_CALLBACK(_use_latest_md_algo_callback), self);
 
   // we put fine-tuning values under an expander
diff --git a/src/iop/levels.c b/src/iop/levels.c
index e13f41cb0599..a7105ff6c9e8 100644
--- a/src/iop/levels.c
+++ b/src/iop/levels.c
@@ -51,7 +51,7 @@ static gboolean dt_iop_levels_button_press(GtkWidget *widget, GdkEventButton *ev
 static gboolean dt_iop_levels_button_release(GtkWidget *widget, GdkEventButton *event, dt_iop_module_t *self);
 static gboolean dt_iop_levels_leave_notify(GtkWidget *widget, GdkEventCrossing *event, dt_iop_module_t *self);
 static gboolean dt_iop_levels_scroll(GtkWidget *widget, GdkEventScroll *event, dt_iop_module_t *self);
-static void dt_iop_levels_autoadjust_callback(GtkRange *range, dt_iop_module_t *self);
+static void dt_iop_levels_autoadjust_callback(GtkWidget *range, dt_iop_module_t *self);
 //static void dt_iop_levels_mode_callback(GtkWidget *combo, gpointer user_data);
 //static void dt_iop_levels_percentiles_callback(GtkWidget *slider, gpointer user_data);
 
@@ -635,16 +635,16 @@ void gui_init(dt_iop_module_t *self)
                                                     "operates on L channel."));
   dt_action_define_iop(self, NULL, N_("levels"), GTK_WIDGET(g->area), NULL);
 
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_levels_area_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(dt_iop_levels_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event", G_CALLBACK(dt_iop_levels_button_release), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(dt_iop_levels_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(dt_iop_levels_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event", G_CALLBACK(dt_iop_levels_scroll), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_levels_area_draw), self);
+  g_signal_connect(g->area, "button-press-event", G_CALLBACK(dt_iop_levels_button_press), self);
+  g_signal_connect(g->area, "button-release-event", G_CALLBACK(dt_iop_levels_button_release), self);
+  g_signal_connect(g->area, "motion-notify-event", G_CALLBACK(dt_iop_levels_motion_notify), self);
+  g_signal_connect(g->area, "leave-notify-event", G_CALLBACK(dt_iop_levels_leave_notify), self);
+  g_signal_connect(g->area, "scroll-event", G_CALLBACK(dt_iop_levels_scroll), self);
 
   GtkWidget *autobutton = gtk_button_new_with_label(_("auto"));
   gtk_widget_set_tooltip_text(autobutton, _("apply auto levels"));
-  g_signal_connect(G_OBJECT(autobutton), "clicked", G_CALLBACK(dt_iop_levels_autoadjust_callback), self);
+  g_signal_connect(autobutton, "clicked", G_CALLBACK(dt_iop_levels_autoadjust_callback), self);
 
   g->blackpick = dt_color_picker_new(self, DT_COLOR_PICKER_POINT, NULL);
   gtk_widget_set_tooltip_text(g->blackpick, _("pick black point from image"));
@@ -976,7 +976,7 @@ static gboolean dt_iop_levels_scroll(GtkWidget *widget, GdkEventScroll *event, d
   return TRUE; // Ensure that scrolling the widget cannot move side panel
 }
 
-static void dt_iop_levels_autoadjust_callback(GtkRange *range, dt_iop_module_t *self)
+static void dt_iop_levels_autoadjust_callback(GtkWidget *range, dt_iop_module_t *self)
 {
   if(darktable.gui->reset) return;
   dt_iop_levels_params_t *p = self->params;
diff --git a/src/iop/lowlight.c b/src/iop/lowlight.c
index 83b747858d4d..2a6130380cb8 100644
--- a/src/iop/lowlight.c
+++ b/src/iop/lowlight.c
@@ -807,12 +807,12 @@ void gui_init(dt_iop_module_t *self)
   dt_action_define_iop(self, NULL, N_("graph"), GTK_WIDGET(g->area), NULL);
   self->widget = dt_gui_vbox(g->area);
 
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(lowlight_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(lowlight_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event", G_CALLBACK(lowlight_button_release), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(lowlight_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(lowlight_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event", G_CALLBACK(lowlight_scrolled), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(lowlight_draw), self);
+  g_signal_connect(g->area, "button-press-event", G_CALLBACK(lowlight_button_press), self);
+  g_signal_connect(g->area, "button-release-event", G_CALLBACK(lowlight_button_release), self);
+  g_signal_connect(g->area, "motion-notify-event", G_CALLBACK(lowlight_motion_notify), self);
+  g_signal_connect(g->area, "leave-notify-event", G_CALLBACK(lowlight_leave_notify), self);
+  g_signal_connect(g->area, "scroll-event", G_CALLBACK(lowlight_scrolled), self);
 
   g->scale_blueness = dt_bauhaus_slider_from_params(self, "blueness");
   dt_bauhaus_slider_set_format(g->scale_blueness, "%");
diff --git a/src/iop/lut3d.c b/src/iop/lut3d.c
index 397eb206b34d..0bbc3c96f517 100644
--- a/src/iop/lut3d.c
+++ b/src/iop/lut3d.c
@@ -1700,8 +1700,8 @@ void gui_init(dt_iop_module_t *self)
     _("the file path (relative to LUT folder) is saved with image (and not the LUT data themselves)"));
 #endif // HAVE_GMIC
   self->widget = dt_gui_vbox(dt_gui_hbox(g->button, dt_gui_expand(g->filepath)));
-  g_signal_connect(G_OBJECT(g->button), "clicked", G_CALLBACK(_button_clicked), self);
-  g_signal_connect(G_OBJECT(g->filepath), "value-changed", G_CALLBACK(_filepath_callback), self);
+  g_signal_connect(g->button, "clicked", G_CALLBACK(_button_clicked), self);
+  g_signal_connect(g->filepath, "value-changed", G_CALLBACK(_filepath_callback), self);
 
 #ifdef HAVE_GMIC
   // text entry
@@ -1730,11 +1730,11 @@ void gui_init(dt_iop_module_t *self)
   gtk_tree_view_append_column((GtkTreeView *)g->lutname, col);
   GtkTreeSelection *selection = gtk_tree_view_get_selection((GtkTreeView *)g->lutname);
   gtk_tree_selection_set_mode(selection, GTK_SELECTION_SINGLE);
-  g->lutname_handler_id = g_signal_connect(G_OBJECT(selection), "changed", G_CALLBACK(_lutname_callback), self);
+  g->lutname_handler_id = g_signal_connect_data(selection, "changed", G_CALLBACK(_lutname_callback), self, NULL, 0);
   dt_gui_box_add(self->widget, g->lutwindow);
 
-  g_signal_connect(G_OBJECT(g->lutentry), "changed", G_CALLBACK(_entry_callback), self);
-  g_signal_connect(G_OBJECT((GtkTreeView *)g->lutname), "scroll-event", G_CALLBACK(_mouse_scroll), (gpointer)self);
+  g_signal_connect(g->lutentry, "changed", G_CALLBACK(_entry_callback), self);
+  g_signal_connect(g->lutname, "scroll-event", G_CALLBACK(_mouse_scroll), self);
 #endif // HAVE_GMIC
 
   g->colorspace = dt_bauhaus_combobox_from_params(self, "colorspace");
diff --git a/src/iop/monochrome.c b/src/iop/monochrome.c
index 4187e14efa91..752454d3a0bb 100644
--- a/src/iop/monochrome.c
+++ b/src/iop/monochrome.c
@@ -562,14 +562,14 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_add_events(GTK_WIDGET(g->area), GDK_POINTER_MOTION_MASK
                                              | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                              | GDK_LEAVE_NOTIFY_MASK | darktable.gui->scroll_mask);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(_monochrome_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(_monochrome_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event", G_CALLBACK(_monochrome_button_release),
+  g_signal_connect(g->area, "draw", G_CALLBACK(_monochrome_draw), self);
+  g_signal_connect(g->area, "button-press-event", G_CALLBACK(_monochrome_button_press), self);
+  g_signal_connect(g->area, "button-release-event", G_CALLBACK(_monochrome_button_release),
                    self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(_monochrome_motion_notify),
+  g_signal_connect(g->area, "motion-notify-event", G_CALLBACK(_monochrome_motion_notify),
                    self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(_monochrome_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event", G_CALLBACK(_monochrome_scrolled), self);
+  g_signal_connect(g->area, "leave-notify-event", G_CALLBACK(_monochrome_leave_notify), self);
+  g_signal_connect(g->area, "scroll-event", G_CALLBACK(_monochrome_scrolled), self);
 
   g->highlights
       = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, dt_bauhaus_slider_from_params(self, N_("highlights")));
diff --git a/src/iop/negadoctor.c b/src/iop/negadoctor.c
index dac037af3d2a..c21efab33b77 100644
--- a/src/iop/negadoctor.c
+++ b/src/iop/negadoctor.c
@@ -843,7 +843,7 @@ void gui_init(dt_iop_module_t *self)
   g->Dmin_picker = gtk_color_button_new();
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->Dmin_picker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->Dmin_picker), _("select color of film material from a swatch"));
-  g_signal_connect(G_OBJECT(g->Dmin_picker), "color-set", G_CALLBACK(Dmin_picker_callback), self);
+  g_signal_connect(g->Dmin_picker, "color-set", G_CALLBACK(Dmin_picker_callback), self);
 
   g->Dmin_sampler = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, NULL);
   gtk_widget_set_tooltip_text(g->Dmin_sampler , _("pick color of film material from image"));
@@ -905,7 +905,7 @@ void gui_init(dt_iop_module_t *self)
   g->WB_low_picker = gtk_color_button_new();
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->WB_low_picker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->WB_low_picker), _("select color of shadows from a swatch"));
-  g_signal_connect(G_OBJECT(g->WB_low_picker), "color-set", G_CALLBACK(WB_low_picker_callback), self);
+  g_signal_connect(g->WB_low_picker, "color-set", G_CALLBACK(WB_low_picker_callback), self);
 
   g->WB_low_sampler = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, NULL);
   gtk_widget_set_tooltip_text(g->WB_low_sampler, _("pick shadows color from image"));
@@ -939,7 +939,7 @@ void gui_init(dt_iop_module_t *self)
   g->WB_high_picker = gtk_color_button_new();
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->WB_high_picker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->WB_high_picker), _("select color of illuminant from a swatch"));
-  g_signal_connect(G_OBJECT(g->WB_high_picker), "color-set", G_CALLBACK(WB_high_picker_callback), self);
+  g_signal_connect(g->WB_high_picker, "color-set", G_CALLBACK(WB_high_picker_callback), self);
 
   g->WB_high_sampler = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, NULL);
   gtk_widget_set_tooltip_text(g->WB_high_sampler , _("pick illuminant color from image"));
diff --git a/src/iop/overlay.c b/src/iop/overlay.c
index 4021887b7004..31b5321e33f3 100644
--- a/src/iop/overlay.c
+++ b/src/iop/overlay.c
@@ -809,7 +809,7 @@ static void _draw_thumb(GtkWidget *area,
   }
 }
 
-static void _alignment_callback(const GtkWidget *tb, dt_iop_module_t *self)
+static void _alignment_callback(GtkWidget *tb, dt_iop_module_t *self)
 {
   const dt_iop_overlay_gui_data_t *g = self->gui_data;
 
@@ -1048,9 +1048,9 @@ static void _drag_and_drop_received(GtkWidget *widget,
 
 static gboolean _on_drag_motion(GtkWidget *widget,
                                 GdkDragContext *dc,
-                                gint x,
-                                gint y,
-                                guint time,
+                                const gint x,
+                                const gint y,
+                                const guint time,
                                 const dt_iop_module_t *self)
 {
   dt_iop_overlay_gui_data_t *g = self->gui_data;
@@ -1082,7 +1082,7 @@ void gui_init(dt_iop_module_t *self)
   int line = 0;
 
   g->area = GTK_DRAWING_AREA(dtgtk_drawing_area_new_with_height(0));
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(_draw_thumb), self);
+  g_signal_connect(g->area, "draw", G_CALLBACK(_draw_thumb), self);
   gtk_widget_set_size_request(GTK_WIDGET(g->area), 150, 150);
   gtk_grid_attach(grid, GTK_WIDGET(g->area), 0, line++, 1, 2);
 
@@ -1155,7 +1155,7 @@ void gui_init(dt_iop_module_t *self)
     g->align[i] = dtgtk_togglebutton_new(dtgtk_cairo_paint_alignment,
                                          (CPF_SPECIAL_FLAG << i), NULL);
     gtk_grid_attach(GTK_GRID(bat), GTK_WIDGET(g->align[i]), 1 + i%3, i/3, 1, 1);
-    g_signal_connect(G_OBJECT(g->align[i]), "toggled",
+    g_signal_connect(g->align[i], "toggled",
                      G_CALLBACK(_alignment_callback), self);
   }
 
diff --git a/src/iop/rasterfile.c b/src/iop/rasterfile.c
index eff4af723367..2bcfa44f1efd 100644
--- a/src/iop/rasterfile.c
+++ b/src/iop/rasterfile.c
@@ -594,12 +594,12 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_name(g->fbutton, "non-flat");
   gtk_widget_set_tooltip_text(g->fbutton, _("select the PFM file recorded as a raster mask,\n"
       "CAUTION: path must be set in preferences/processing before choosing"));
-  g_signal_connect(G_OBJECT(g->fbutton), "clicked", G_CALLBACK(_fbutton_clicked), self);
+  g_signal_connect(g->fbutton, "clicked", G_CALLBACK(_fbutton_clicked), self);
 
   g->file = dt_bauhaus_combobox_new(self);
   dt_bauhaus_combobox_set_entries_ellipsis(g->file, PANGO_ELLIPSIZE_MIDDLE);
   gtk_widget_set_tooltip_text(g->file, _("the mask file path is saved with the image history"));
-  g_signal_connect(G_OBJECT(g->file), "value-changed", G_CALLBACK(_file_callback), self);
+  g_signal_connect(g->file, "value-changed", G_CALLBACK(_file_callback), self);
 
   dt_gui_box_add(self->widget, dt_gui_hbox(g->fbutton, dt_gui_expand(g->file)));
 }
diff --git a/src/iop/rawdenoise.c b/src/iop/rawdenoise.c
index 59779cb76276..9fff652d73ff 100644
--- a/src/iop/rawdenoise.c
+++ b/src/iop/rawdenoise.c
@@ -886,7 +886,7 @@ void gui_init(dt_iop_module_t *self)
 
   gtk_widget_show(gtk_notebook_get_nth_page(g->channel_tabs, g->channel));
   gtk_notebook_set_current_page(g->channel_tabs, g->channel);
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page", G_CALLBACK(rawdenoise_tab_switch), self);
+  g_signal_connect(g->channel_tabs, "switch-page", G_CALLBACK(rawdenoise_tab_switch), self);
 
   const int ch = (int)g->channel;
   g->transition_curve = dt_draw_curve_new(0.0, 1.0, CATMULL_ROM);
@@ -909,12 +909,12 @@ void gui_init(dt_iop_module_t *self)
 
   GtkWidget *box_raw = self->widget = dt_gui_vbox(g->channel_tabs, g->area);
 
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(rawdenoise_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(rawdenoise_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event", G_CALLBACK(rawdenoise_button_release), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(rawdenoise_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(rawdenoise_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event", G_CALLBACK(rawdenoise_scrolled), self);
+  g_signal_connect(GTK_WIDGET(g->area), "draw", G_CALLBACK(rawdenoise_draw), self);
+  g_signal_connect(GTK_WIDGET(g->area), "button-press-event", G_CALLBACK(rawdenoise_button_press), self);
+  g_signal_connect(GTK_WIDGET(g->area), "button-release-event", G_CALLBACK(rawdenoise_button_release), self);
+  g_signal_connect(GTK_WIDGET(g->area), "motion-notify-event", G_CALLBACK(rawdenoise_motion_notify), self);
+  g_signal_connect(GTK_WIDGET(g->area), "leave-notify-event", G_CALLBACK(rawdenoise_leave_notify), self);
+  g_signal_connect(GTK_WIDGET(g->area), "scroll-event", G_CALLBACK(rawdenoise_scrolled), self);
 
   g->threshold = dt_bauhaus_slider_from_params(self, "threshold");
   dt_bauhaus_slider_set_soft_max(g->threshold, 0.1);
diff --git a/src/iop/relight.c b/src/iop/relight.c
index ada80a8ea71d..c01abe1e25cd 100644
--- a/src/iop/relight.c
+++ b/src/iop/relight.c
@@ -256,7 +256,7 @@ void gui_init(dt_iop_module_t *self)
 
   g->center = DTGTK_GRADIENT_SLIDER(dtgtk_gradient_slider_new_with_color_and_name(_gradient_L[0], _gradient_L[1], "gslider-relight"));
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->center), _("select the center of fill-light\nctrl+click to select an area"));
-  g_signal_connect(G_OBJECT(g->center), "value-changed", G_CALLBACK(center_callback), self);
+  g_signal_connect(g->center, "value-changed", G_CALLBACK(center_callback), self);
   g->colorpicker = dt_color_picker_new(self, DT_COLOR_PICKER_POINT_AREA, NULL);
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->colorpicker), _("toggle tool for picking median lightness in image"));
   dt_gui_box_add(self->widget, dt_gui_hbox(dt_gui_expand(g->center), g->colorpicker));
diff --git a/src/iop/retouch.c b/src/iop/retouch.c
index aaf026bcb243..3635656de6f6 100644
--- a/src/iop/retouch.c
+++ b/src/iop/retouch.c
@@ -2531,17 +2531,17 @@ void gui_init(dt_iop_module_t *self)
        "top line indicates that the scale is visible at current zoom level\n"
        "bottom line indicates that the scale has shapes on it"));
 
-  g_signal_connect(G_OBJECT(g->wd_bar), "draw",
+  g_signal_connect(g->wd_bar, "draw",
                    G_CALLBACK(rt_wdbar_draw), self);
-  g_signal_connect(G_OBJECT(g->wd_bar), "motion-notify-event",
+  g_signal_connect(g->wd_bar, "motion-notify-event",
                    G_CALLBACK(rt_wdbar_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->wd_bar), "leave-notify-event",
+  g_signal_connect(g->wd_bar, "leave-notify-event",
                    G_CALLBACK(rt_wdbar_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->wd_bar), "button-press-event",
+  g_signal_connect(g->wd_bar, "button-press-event",
                    G_CALLBACK(rt_wdbar_button_press), self);
-  g_signal_connect(G_OBJECT(g->wd_bar), "button-release-event",
+  g_signal_connect(g->wd_bar, "button-release-event",
                    G_CALLBACK(rt_wdbar_button_release), self);
-  g_signal_connect(G_OBJECT(g->wd_bar), "scroll-event",
+  g_signal_connect(g->wd_bar, "scroll-event",
                    G_CALLBACK(rt_wdbar_scrolled), self);
   gtk_widget_add_events(GTK_WIDGET(g->wd_bar),
                         GDK_POINTER_MOTION_MASK
@@ -2606,7 +2606,7 @@ void gui_init(dt_iop_module_t *self)
   dtgtk_gradient_slider_multivalue_set_resetvalues(gslider, vdefault);
   (gslider)->markers_type = PROPORTIONAL_MARKERS;
   (gslider)->min_spacing = 0.05;
-  g_signal_connect(G_OBJECT(gslider), "value-changed",
+  g_signal_connect(gslider, "value-changed",
                    G_CALLBACK(rt_gslider_changed), self);
 
   // auto-levels button
@@ -2645,7 +2645,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(g->colorpick), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(g->colorpick), _("select fill color"));
   gtk_widget_set_tooltip_text(g->colorpick, _("select fill color"));
-  g_signal_connect(G_OBJECT(g->colorpick), "color-set",
+  g_signal_connect(g->colorpick, "color-set",
                    G_CALLBACK(rt_colorpick_color_set_callback), self);
 
   g->colorpicker = dt_color_picker_new
@@ -2683,7 +2683,7 @@ void gui_init(dt_iop_module_t *self)
   dt_bauhaus_slider_set_format(g->sl_mask_opacity, "%");
   gtk_widget_set_tooltip_text(g->sl_mask_opacity,
                               _("set the opacity on the selected shape"));
-  g_signal_connect(G_OBJECT(g->sl_mask_opacity), "value-changed",
+  g_signal_connect(g->sl_mask_opacity, "value-changed",
                    G_CALLBACK(rt_mask_opacity_callback), self);
 
   // start building top level widget
diff --git a/src/iop/rgbcurve.c b/src/iop/rgbcurve.c
index a976f5fec56a..2459853198e5 100644
--- a/src/iop/rgbcurve.c
+++ b/src/iop/rgbcurve.c
@@ -1489,7 +1489,7 @@ void gui_init(dt_iop_module_t *self)
   dt_ui_notebook_page(g->channel_tabs, N_("R"), _("curve nodes for r channel"));
   dt_ui_notebook_page(g->channel_tabs, N_("G"), _("curve nodes for g channel"));
   dt_ui_notebook_page(g->channel_tabs, N_("B"), _("curve nodes for b channel"));
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page",
+  g_signal_connect(g->channel_tabs, "switch-page",
                    G_CALLBACK(tab_switch_callback), self);
 
   // color pickers
@@ -1532,17 +1532,17 @@ void gui_init(dt_iop_module_t *self)
                         | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                         | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw",
+  g_signal_connect(g->area, "draw",
                    G_CALLBACK(_area_draw_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(_area_button_press_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(_area_motion_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(g->area, "leave-notify-event",
                    G_CALLBACK(_area_leave_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(_area_scrolled_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "key-press-event",
+  g_signal_connect(g->area, "key-press-event",
                    G_CALLBACK(_area_key_press_callback), self);
 
   g->interpolator = dt_bauhaus_combobox_new_interpolation(self);
@@ -1551,7 +1551,7 @@ void gui_init(dt_iop_module_t *self)
         "- cubic spline is better to produce smooth curves but oscillates when nodes are too close\n"
         "- centripetal is better to avoids cusps and oscillations with close nodes but is less smooth\n"
         "- monotonic is better for accuracy of pure analytical functions (log, gamma, exp)"));
-  g_signal_connect(G_OBJECT(g->interpolator), "value-changed",
+  g_signal_connect(g->interpolator, "value-changed",
                    G_CALLBACK(interpolator_callback), self);
 
   dt_gui_box_add(self->widget, dt_gui_hbox(dt_gui_expand(g->channel_tabs),
diff --git a/src/iop/rgblevels.c b/src/iop/rgblevels.c
index 1a7aeafb46ad..f0a705e3c153 100644
--- a/src/iop/rgblevels.c
+++ b/src/iop/rgblevels.c
@@ -1039,7 +1039,7 @@ void gui_init(dt_iop_module_t *self)
   dt_ui_notebook_page(g->channel_tabs, N_("R"), _("curve nodes for r channel"));
   dt_ui_notebook_page(g->channel_tabs, N_("G"), _("curve nodes for g channel"));
   dt_ui_notebook_page(g->channel_tabs, N_("B"), _("curve nodes for b channel"));
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page",
+  g_signal_connect(g->channel_tabs, "switch-page",
                    G_CALLBACK(_tab_switch_callback), self);
 
   g->area = GTK_DRAWING_AREA(dt_ui_resize_wrap(NULL,
@@ -1052,17 +1052,17 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->area),
                               _("drag handles to set black, gray, and white points. "
                                 "operates on L channel."));
-  g_signal_connect(G_OBJECT(g->area), "draw",
+  g_signal_connect(g->area, "draw",
                    G_CALLBACK(_area_draw_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(_area_button_press_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event",
+  g_signal_connect(g->area, "button-release-event",
                    G_CALLBACK(_area_button_release_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(_area_motion_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(g->area, "leave-notify-event",
                    G_CALLBACK(_area_leave_notify_callback), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(_area_scroll_callback), self);
 
 #define PICKER_SETUP(color, name, tooltip)                                 \
@@ -1096,9 +1096,9 @@ void gui_init(dt_iop_module_t *self)
                  dt_gui_hbox(g->blackpick, g->greypick, g->whitepick),
                  dt_gui_hbox(dt_gui_expand(g->bt_auto_levels), dt_gui_expand(g->bt_select_region)));
 
-  g_signal_connect(G_OBJECT(g->bt_auto_levels), "clicked",
+  g_signal_connect(g->bt_auto_levels, "clicked",
                    G_CALLBACK(_auto_levels_callback), self);
-  g_signal_connect(G_OBJECT(g->bt_select_region), "toggled",
+  g_signal_connect(g->bt_select_region, "toggled",
                    G_CALLBACK(_select_region_toggled_callback), self);
 
   g->cmb_preserve_colors = dt_bauhaus_combobox_from_params(self, "preserve_colors");
diff --git a/src/iop/splittoning.c b/src/iop/splittoning.c
index d977ffc1e74e..7ac941d50df7 100644
--- a/src/iop/splittoning.c
+++ b/src/iop/splittoning.c
@@ -475,7 +475,7 @@ static inline void gui_init_section(dt_iop_module_t *self,
   *picker = gtk_color_button_new();
   gtk_color_chooser_set_use_alpha(GTK_COLOR_CHOOSER(*picker), FALSE);
   gtk_color_button_set_title(GTK_COLOR_BUTTON(*picker), _("select tone color"));
-  g_signal_connect(G_OBJECT(*picker), "color-set", G_CALLBACK(colorpick_callback), self);
+  g_signal_connect(*picker, "color-set", G_CALLBACK(colorpick_callback), self);
 
   dt_gui_box_add(self->widget, dt_ui_section_label_new(Q_(section)),
                  dt_gui_hbox(dt_gui_expand(slider_box), *picker));
diff --git a/src/iop/temperature.c b/src/iop/temperature.c
index 4b7c5a7cd0ff..dc0058636974 100644
--- a/src/iop/temperature.c
+++ b/src/iop/temperature.c
@@ -2145,7 +2145,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->temp_label, _("click to cycle color mode on sliders"));
   gtk_container_add(GTK_CONTAINER(temp_label_box), g->temp_label);
 
-  g_signal_connect(G_OBJECT(temp_label_box), "button-release-event",
+  g_signal_connect(temp_label_box, "button-release-event",
                    G_CALLBACK(temp_label_click), self);
 
   //Match UI order: temp first, then tint (like every other app ever)
@@ -2190,14 +2190,14 @@ void gui_init(dt_iop_module_t *self)
 
   gtk_widget_set_no_show_all(g->scale_y, TRUE);
 
-  g_signal_connect(G_OBJECT(g->scale_k), "value-changed",
+  g_signal_connect(g->scale_k, "value-changed",
                    G_CALLBACK(_temp_tint_callback), self);
-  g_signal_connect(G_OBJECT(g->scale_tint), "value-changed",
+  g_signal_connect(g->scale_tint, "value-changed",
                    G_CALLBACK(_temp_tint_callback), self);
 
-  g_signal_connect(G_OBJECT(g->presets), "value-changed",
+  g_signal_connect(g->presets, "value-changed",
                    G_CALLBACK(_preset_tune_callback), self);
-  g_signal_connect(G_OBJECT(g->finetune), "value-changed",
+  g_signal_connect(g->finetune, "value-changed",
                    G_CALLBACK(_preset_tune_callback), self);
 
   // update the gui when the preferences changed (i.e. colored sliders stuff)
diff --git a/src/iop/tonecurve.c b/src/iop/tonecurve.c
index 73b41414caab..4f26ea2ee0b7 100644
--- a/src/iop/tonecurve.c
+++ b/src/iop/tonecurve.c
@@ -1270,7 +1270,7 @@ void gui_init(dt_iop_module_t *self)
   dt_ui_notebook_page(g->channel_tabs, N_("L"), _("tonecurve for L channel"));
   dt_ui_notebook_page(g->channel_tabs, N_("a"), _("tonecurve for a channel"));
   dt_ui_notebook_page(g->channel_tabs, N_("b"), _("tonecurve for b channel"));
-  g_signal_connect(G_OBJECT(g->channel_tabs), "switch_page", G_CALLBACK(tab_switch), self);
+  g_signal_connect(g->channel_tabs, "switch-page", G_CALLBACK(tab_switch), self);
 
   g->colorpicker = dt_color_picker_new(self,
                                        DT_COLOR_PICKER_POINT_AREA | DT_COLOR_PICKER_IO,
@@ -1294,16 +1294,16 @@ void gui_init(dt_iop_module_t *self)
                                            | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                            | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "draw", G_CALLBACK(dt_iop_tonecurve_draw), self);
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(dt_iop_tonecurve_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(dt_iop_tonecurve_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(g->area, "leave-notify-event",
                    G_CALLBACK(dt_iop_tonecurve_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(_scrolled), self);
-  g_signal_connect(G_OBJECT(g->area), "key-press-event",
+  g_signal_connect(g->area, "key-press-event",
                    G_CALLBACK(dt_iop_tonecurve_key_press), self);
 
   g->interpolator = dt_bauhaus_combobox_new_interpolation(self);
@@ -1313,7 +1313,7 @@ void gui_init(dt_iop_module_t *self)
        "- cubic spline is better to produce smooth curves but oscillates when nodes are too close\n"
        "- centripetal is better to avoids cusps and oscillations with close nodes but is less smooth\n"
        "- monotonic is better for accuracy of pure analytical functions (log, gamma, exp)"));
-  g_signal_connect(G_OBJECT(g->interpolator), "value-changed",
+  g_signal_connect(g->interpolator, "value-changed",
                    G_CALLBACK(interpolator_callback), self);
 
   dt_gui_box_add(self->widget, g->area, g->interpolator);
@@ -1325,7 +1325,7 @@ void gui_init(dt_iop_module_t *self)
   g->logbase = dt_bauhaus_slider_new_with_range(self, 0.0f, 40.0f, 0, 0.0f, 2);
   dt_bauhaus_widget_set_label(g->logbase, NULL, N_("scale for graph"));
   dt_gui_box_add(self->widget, g->logbase);
-  g_signal_connect(G_OBJECT(g->logbase), "value-changed",
+  g_signal_connect(g->logbase, "value-changed",
                    G_CALLBACK(logbase_callback), self);
 
   g->sizegroup = GTK_SIZE_GROUP(gtk_size_group_new(GTK_SIZE_GROUP_HORIZONTAL));
diff --git a/src/iop/toneequal.c b/src/iop/toneequal.c
index 81a29351fdf8..6259136e0383 100644
--- a/src/iop/toneequal.c
+++ b/src/iop/toneequal.c
@@ -3284,18 +3284,18 @@ void gui_init(dt_iop_module_t *self)
                         | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
   gtk_widget_set_vexpand(GTK_WIDGET(g->area), TRUE);
   gtk_widget_set_can_focus(GTK_WIDGET(g->area), TRUE);
-  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(area_draw), self);
-  g_signal_connect(G_OBJECT(g->area), "button-press-event",
+  g_signal_connect(g->area, "draw", G_CALLBACK(area_draw), self);
+  g_signal_connect(g->area, "button-press-event",
                    G_CALLBACK(area_button_press), self);
-  g_signal_connect(G_OBJECT(g->area), "button-release-event",
+  g_signal_connect(g->area, "button-release-event",
                    G_CALLBACK(area_button_release), self);
-  g_signal_connect(G_OBJECT(g->area), "leave-notify-event",
+  g_signal_connect(g->area, "leave-notify-event",
                    G_CALLBACK(area_enter_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "enter-notify-event",
+  g_signal_connect(g->area, "enter-notify-event",
                    G_CALLBACK(area_enter_leave_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "motion-notify-event",
+  g_signal_connect(g->area, "motion-notify-event",
                    G_CALLBACK(area_motion_notify), self);
-  g_signal_connect(G_OBJECT(g->area), "scroll-event",
+  g_signal_connect(g->area, "scroll-event",
                    G_CALLBACK(area_scroll), self);
   gtk_widget_set_tooltip_text(GTK_WIDGET(g->area), _("double-click to reset the curve"));
 
@@ -3308,7 +3308,7 @@ void gui_init(dt_iop_module_t *self)
        "but the curve might become oscillatory in some settings.\n"
        "negative values will avoid oscillations and behave more robustly\n"
        "but may produce brutal tone transitions and damage local contrast."));
-  g_signal_connect(G_OBJECT(g->smoothing), "value-changed",
+  g_signal_connect(g->smoothing, "value-changed",
                    G_CALLBACK(smoothing_callback), self);
   dt_gui_box_add(self->widget, wrapper, g->smoothing);
   
@@ -3396,7 +3396,7 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_show(gtk_notebook_get_nth_page(g->notebook, active_page));
   gtk_notebook_set_current_page(g->notebook, active_page);
 
-  g_signal_connect(G_OBJECT(g->notebook), "button-press-event",
+  g_signal_connect(g->notebook, "button-press-event",
                    G_CALLBACK(notebook_button_press), self);
 
   g->show_luminance_mask = dt_iop_togglebutton_new
diff --git a/src/iop/useless.c b/src/iop/useless.c
index 1199be73bca0..716bc37aa122 100644
--- a/src/iop/useless.c
+++ b/src/iop/useless.c
@@ -688,7 +688,7 @@ void gui_init(dt_iop_module_t *self)
   g->extra = dt_bauhaus_slider_new_with_range(self, -0.5, 0.5, 0, 0, 2);
   dt_bauhaus_widget_set_label(g->extra, NULL, N_("extra"));
   dt_gui_box_add(self->widget, g->extra);
-  g_signal_connect(G_OBJECT(g->extra), "value-changed", G_CALLBACK(extra_callback), self);
+  g_signal_connect(g->extra, "value-changed", G_CALLBACK(extra_callback), self);
 }
 
 void gui_cleanup(dt_iop_module_t *self)
diff --git a/src/iop/watermark.c b/src/iop/watermark.c
index 31b121441a50..8aa1718ea62f 100644
--- a/src/iop/watermark.c
+++ b/src/iop/watermark.c
@@ -1124,7 +1124,7 @@ static void _refresh_callback(GtkWidget *tb, dt_iop_module_t *self)
   _refresh_watermarks(self);
 }
 
-static void _alignment_callback(const GtkWidget *tb, dt_iop_module_t *self)
+static void _alignment_callback(GtkWidget *tb, dt_iop_module_t *self)
 {
   int index = -1;
   const dt_iop_watermark_gui_data_t *g = self->gui_data;
@@ -1410,7 +1410,7 @@ void gui_init(dt_iop_module_t *self)
   {
     g->align[i] = dtgtk_togglebutton_new(dtgtk_cairo_paint_alignment, (CPF_SPECIAL_FLAG << i), NULL);
     gtk_grid_attach(GTK_GRID(bat), GTK_WIDGET(g->align[i]), 1 + i%3, i/3, 1, 1);
-    g_signal_connect(G_OBJECT(g->align[i]), "toggled", G_CALLBACK(_alignment_callback), self);
+    g_signal_connect(g->align[i], "toggled", G_CALLBACK(_alignment_callback), self);
   }
 
   dt_gui_box_add(self->widget, bat);
@@ -1428,10 +1428,10 @@ void gui_init(dt_iop_module_t *self)
 
   _refresh_watermarks(self);
 
-  g_signal_connect(G_OBJECT(g->watermarks), "value-changed", G_CALLBACK(_watermark_callback), self);
-  g_signal_connect(G_OBJECT(g->refresh), "clicked", G_CALLBACK(_refresh_callback), self);
-  g_signal_connect(G_OBJECT(g->colorpick), "color-set", G_CALLBACK(_colorpick_color_set), self);
-  g_signal_connect(G_OBJECT(g->fontsel), "font-set", G_CALLBACK(_fontsel_callback), self);
+  g_signal_connect(g->watermarks, "value-changed", G_CALLBACK(_watermark_callback), self);
+  g_signal_connect(g->refresh, "clicked", G_CALLBACK(_refresh_callback), self);
+  g_signal_connect(g->colorpick, "color-set", G_CALLBACK(_colorpick_color_set), self);
+  g_signal_connect(g->fontsel, "font-set", G_CALLBACK(_fontsel_callback), self);
 }
 
 void gui_cleanup(dt_iop_module_t *self)
diff --git a/src/iop/zonesystem.c b/src/iop/zonesystem.c
index 3adb8be831d8..0e064a925e78 100644
--- a/src/iop/zonesystem.c
+++ b/src/iop/zonesystem.c
@@ -430,8 +430,8 @@ void gui_init(dt_iop_module_t *self)
   g->mouse_over_output_zones = FALSE;
 
   g->preview = dtgtk_drawing_area_new_with_height(0);
-  g_signal_connect(G_OBJECT(g->preview), "size-allocate", G_CALLBACK(size_allocate_callback), self);
-  g_signal_connect(G_OBJECT(g->preview), "draw", G_CALLBACK(dt_iop_zonesystem_preview_draw), self);
+  g_signal_connect(g->preview, "size-allocate", G_CALLBACK(size_allocate_callback), self);
+  g_signal_connect(g->preview, "draw", G_CALLBACK(dt_iop_zonesystem_preview_draw), self);
   gtk_widget_add_events(GTK_WIDGET(g->preview), GDK_POINTER_MOTION_MASK
                                                 | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                                 | GDK_LEAVE_NOTIFY_MASK);
@@ -441,16 +441,16 @@ void gui_init(dt_iop_module_t *self)
   gtk_widget_set_tooltip_text(g->zones, _("lightness zones\nuse mouse scrollwheel to change the number of zones\n"
                                           "left-click on a border to create a marker\n"
                                           "right-click on a marker to delete it"));
-  g_signal_connect(G_OBJECT(g->zones), "draw", G_CALLBACK(dt_iop_zonesystem_bar_draw), self);
-  g_signal_connect(G_OBJECT(g->zones), "motion-notify-event", G_CALLBACK(dt_iop_zonesystem_bar_motion_notify),
+  g_signal_connect(g->zones, "draw", G_CALLBACK(dt_iop_zonesystem_bar_draw), self);
+  g_signal_connect(g->zones, "motion-notify-event", G_CALLBACK(dt_iop_zonesystem_bar_motion_notify),
                    self);
-  g_signal_connect(G_OBJECT(g->zones), "leave-notify-event", G_CALLBACK(dt_iop_zonesystem_bar_leave_notify),
+  g_signal_connect(g->zones, "leave-notify-event", G_CALLBACK(dt_iop_zonesystem_bar_leave_notify),
                    self);
-  g_signal_connect(G_OBJECT(g->zones), "button-press-event", G_CALLBACK(dt_iop_zonesystem_bar_button_press),
+  g_signal_connect(g->zones, "button-press-event", G_CALLBACK(dt_iop_zonesystem_bar_button_press),
                    self);
-  g_signal_connect(G_OBJECT(g->zones), "button-release-event",
+  g_signal_connect(g->zones, "button-release-event",
                    G_CALLBACK(dt_iop_zonesystem_bar_button_release), self);
-  g_signal_connect(G_OBJECT(g->zones), "scroll-event", G_CALLBACK(dt_iop_zonesystem_bar_scrolled), self);
+  g_signal_connect(g->zones, "scroll-event", G_CALLBACK(dt_iop_zonesystem_bar_scrolled), self);
   gtk_widget_add_events(GTK_WIDGET(g->zones), GDK_POINTER_MOTION_MASK
                                               | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                               | GDK_LEAVE_NOTIFY_MASK | darktable.gui->scroll_mask);
diff --git a/src/libs/backgroundjobs.c b/src/libs/backgroundjobs.c
index b791f704293f..d7548dbf6f21 100644
--- a/src/libs/backgroundjobs.c
+++ b/src/libs/backgroundjobs.c
@@ -239,7 +239,7 @@ static gboolean _cancellable_gui_thread(gpointer user_data)
 
   GtkBox *hbox = GTK_BOX(params->instance->hbox);
   GtkWidget *button = dtgtk_button_new(dtgtk_cairo_paint_cancel, 0, NULL);
-  g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(_lib_backgroundjobs_cancel_callback_new), params->progress);
+  g_signal_connect(button, "clicked", G_CALLBACK(_lib_backgroundjobs_cancel_callback_new), params->progress);
   gtk_box_pack_start(hbox, GTK_WIDGET(button), FALSE, FALSE, 0);
   gtk_widget_show_all(button);
 
diff --git a/src/libs/camera.c b/src/libs/camera.c
index c6a580dcc65e..2289cc255ef1 100644
--- a/src/libs/camera.c
+++ b/src/libs/camera.c
@@ -144,7 +144,7 @@ static dt_lib_camera_property_t *_lib_property_add_new(dt_lib_camera_t *lib,
       lib->gui.properties = g_list_append(lib->gui.properties, prop);
 
       // Does dead lock!!!
-      g_signal_connect(G_OBJECT(prop->values), "value-changed", G_CALLBACK(property_changed_callback),
+      g_signal_connect(prop->values, "value-changed", G_CALLBACK(property_changed_callback),
                        (gpointer)prop);
       return prop;
     }
@@ -263,7 +263,7 @@ static void _lib_property_add_to_gui(dt_lib_camera_property_t *prop, dt_lib_came
   gtk_box_pack_start(GTK_BOX(hbox), GTK_WIDGET(prop->osd), FALSE, FALSE, 0);
   gtk_grid_insert_row(lib->gui.main_grid, lib->gui.prop_end); // make space for the new row
   gtk_grid_attach(lib->gui.main_grid, GTK_WIDGET(hbox), 0, lib->gui.prop_end, 2, 1);
-  g_signal_connect(G_OBJECT(prop->osd), "clicked", G_CALLBACK(_osd_button_clicked), prop);
+  g_signal_connect(prop->osd, "clicked", G_CALLBACK(_osd_button_clicked), prop);
   gtk_widget_show_all(GTK_WIDGET(hbox));
   lib->gui.rows++;
   lib->gui.prop_end++;
@@ -494,9 +494,9 @@ void gui_init(dt_lib_module_t *self)
                _("the amount of steps per bracket, steps is camera configurable and usually 3 steps per "
                  "stop\nwith other words, 3 steps is 1EV exposure step between brackets"));
 
-  g_signal_connect(G_OBJECT(lib->gui.toggle_timer), "clicked", G_CALLBACK(_toggle_capture_mode_clicked), lib);
-  g_signal_connect(G_OBJECT(lib->gui.toggle_sequence), "clicked", G_CALLBACK(_toggle_capture_mode_clicked), lib);
-  g_signal_connect(G_OBJECT(lib->gui.toggle_bracket), "clicked", G_CALLBACK(_toggle_capture_mode_clicked), lib);
+  g_signal_connect(lib->gui.toggle_timer, "clicked", G_CALLBACK(_toggle_capture_mode_clicked), lib);
+  g_signal_connect(lib->gui.toggle_sequence, "clicked", G_CALLBACK(_toggle_capture_mode_clicked), lib);
+  g_signal_connect(lib->gui.toggle_bracket, "clicked", G_CALLBACK(_toggle_capture_mode_clicked), lib);
 
   gtk_widget_set_sensitive(GTK_WIDGET(lib->gui.timer), FALSE);
   gtk_widget_set_sensitive(GTK_WIDGET(lib->gui.count), FALSE);
@@ -527,7 +527,7 @@ void gui_init(dt_lib_module_t *self)
   label = gtk_label_new(_("property"));
   gtk_widget_set_halign(label, GTK_ALIGN_START);
   GtkWidget *widget = gtk_button_new_with_label("O");
-  g_signal_connect(G_OBJECT(widget), "clicked", G_CALLBACK(_show_property_popupmenu_clicked), lib);
+  g_signal_connect(widget, "clicked", G_CALLBACK(_show_property_popupmenu_clicked), lib);
   lib->gui.pname = dt_ui_entry_new(0);
   gtk_box_pack_start(hbox, GTK_WIDGET(lib->gui.pname), TRUE, TRUE, 0);
   gtk_box_pack_start(hbox, GTK_WIDGET(widget), FALSE, FALSE, 0);
@@ -536,7 +536,7 @@ void gui_init(dt_lib_module_t *self)
 
 
   widget = gtk_button_new_with_label(_("add user property"));
-  g_signal_connect(G_OBJECT(widget), "clicked", G_CALLBACK(_add_property_button_clicked), lib);
+  g_signal_connect(widget, "clicked", G_CALLBACK(_add_property_button_clicked), lib);
   gtk_widget_show(widget);
   gtk_grid_attach(GTK_GRID(self->widget), GTK_WIDGET(widget), 0, lib->gui.rows++, 2, 1);
 }
diff --git a/src/libs/collect.c b/src/libs/collect.c
index 9bda03e14e18..4d5ea58875f7 100644
--- a/src/libs/collect.c
+++ b/src/libs/collect.c
@@ -136,7 +136,7 @@ static void _lib_collect_gui_update(dt_lib_module_t *self);
 
 static void _lib_folders_update_collection(const gchar *filmroll);
 
-static void entry_changed(GtkEntry *entry, dt_lib_collect_rule_t *dr);
+static void entry_changed(GtkWidget *entry, dt_lib_collect_rule_t *dr);
 
 static void collection_updated(gpointer instance,
                                dt_collection_change_t query_change,
@@ -406,9 +406,8 @@ uint32_t container(dt_lib_module_t *self)
 }
 
 static void view_popup_menu_onSearchFilmroll(GtkWidget *menuitem,
-                                             gpointer userdata)
+                                             GtkTreeView *treeview)
 {
-  GtkTreeView *treeview = GTK_TREE_VIEW(userdata);
   GtkWidget *win = dt_ui_main_window(darktable.gui->ui);
 
   GtkTreeSelection *selection;
@@ -588,13 +587,13 @@ static void view_popup_menu(GtkWidget *treeview,
 
   menuitem = gtk_menu_item_new_with_label(_("update path to files..."));
   g_signal_connect(menuitem, "activate",
-                   (GCallback)view_popup_menu_onSearchFilmroll, treeview);
+                   G_CALLBACK(view_popup_menu_onSearchFilmroll), treeview);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
 
   menuitem = gtk_menu_item_new_with_label(_("remove..."));
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
   g_signal_connect(menuitem, "activate",
-                   (GCallback)view_popup_menu_onRemove, treeview);
+                   G_CALLBACK(view_popup_menu_onRemove), treeview);
 
   gtk_widget_show_all(GTK_WIDGET(menu));
 
@@ -2900,7 +2899,7 @@ static void entry_activated(GtkWidget *entry,
   dt_control_queue_redraw_center();
 }
 
-static void entry_changed(GtkEntry *entry,
+static void entry_changed(GtkWidget *entry,
                           dt_lib_collect_rule_t *dr)
 {
   dr->typing = TRUE;
@@ -3247,7 +3246,7 @@ static gboolean popup_button_callback(GtkWidget *widget,
 
   mi = gtk_menu_item_new_with_label(_("clear this rule"));
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-  g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(menuitem_clear), d);
+  g_signal_connect(mi, "activate", G_CALLBACK(menuitem_clear), d);
 
   if(d->num == active - 1)
   {
@@ -3255,21 +3254,21 @@ static gboolean popup_button_callback(GtkWidget *widget,
     g_object_set_data(G_OBJECT(mi), "menuitem_mode",
                       GINT_TO_POINTER(DT_LIB_COLLECT_MODE_AND));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(menuitem_mode), d);
 
     mi = gtk_menu_item_new_with_label(_("add more images"));
     g_object_set_data(G_OBJECT(mi), "menuitem_mode",
                       GINT_TO_POINTER(DT_LIB_COLLECT_MODE_OR));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(menuitem_mode), d);
 
     mi = gtk_menu_item_new_with_label(_("exclude images"));
     g_object_set_data(G_OBJECT(mi), "menuitem_mode",
                       GINT_TO_POINTER(DT_LIB_COLLECT_MODE_AND_NOT));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(menuitem_mode), d);
   }
   else if(d->num < active - 1)
@@ -3278,21 +3277,21 @@ static gboolean popup_button_callback(GtkWidget *widget,
     g_object_set_data(G_OBJECT(mi), "menuitem_mode",
                       GINT_TO_POINTER(DT_LIB_COLLECT_MODE_AND));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(menuitem_mode_change), d);
 
     mi = gtk_menu_item_new_with_label(_("change to: or"));
     g_object_set_data(G_OBJECT(mi), "menuitem_mode",
                       GINT_TO_POINTER(DT_LIB_COLLECT_MODE_OR));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(menuitem_mode_change), d);
 
     mi = gtk_menu_item_new_with_label(_("change to: except"));
     g_object_set_data(G_OBJECT(mi), "menuitem_mode",
                       GINT_TO_POINTER(DT_LIB_COLLECT_MODE_AND_NOT));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(menuitem_mode_change), d);
   }
 
@@ -3401,7 +3400,7 @@ void set_preferences(void *menu,
                      dt_lib_module_t *self)
 {
   GtkWidget *mi = gtk_menu_item_new_with_label(_("preferences..."));
-  g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(_menuitem_preferences), self);
+  g_signal_connect(mi, "activate", G_CALLBACK(_menuitem_preferences), self);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
 
@@ -3590,7 +3589,7 @@ static void _history_show(GtkWidget *widget,
       GtkWidget *child = gtk_bin_get_child(GTK_BIN(smt));
       gtk_label_set_use_markup(GTK_LABEL(child), TRUE);
       g_object_set_data(G_OBJECT(smt), "history", GINT_TO_POINTER(i));
-      g_signal_connect(G_OBJECT(smt), "activate", G_CALLBACK(_history_apply), self);
+      g_signal_connect(smt, "activate", G_CALLBACK(_history_apply), self);
       gtk_menu_shell_append(pop, smt);
     }
     else
@@ -3643,7 +3642,7 @@ GtkWidget *gui_tool_box(dt_lib_module_t *self)
   gtk_widget_set_tooltip_text(sortb, _("toggle collection sort order ascending/descending"));
   dt_gui_add_class(sortb, "dt_ignore_fg_state");
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(sortb), sort_descend);
-  g_signal_connect(G_OBJECT(sortb),
+  g_signal_connect(DTGTK_TOGGLEBUTTON(sortb),
                    "toggled",
                    G_CALLBACK(_sort_reverse_changed), self);
   return sortb;
@@ -3674,21 +3673,21 @@ void gui_init(dt_lib_module_t *self)
     dt_bauhaus_combobox_mute_scrolling(w);
     if(_combo_get_active_collection(w) == DT_COLLECTION_PROP_MODULE)
       has_iop_name_rule = TRUE;
-    g_signal_connect(G_OBJECT(w), "value-changed",
+    g_signal_connect(w, "value-changed",
                      G_CALLBACK(combo_changed), d->rule + i);
 
     d->rule[i].text = w = dt_ui_entry_new(10);
     gtk_widget_add_events(w, GDK_FOCUS_CHANGE_MASK | GDK_KEY_PRESS_MASK);
-    g_signal_connect(G_OBJECT(w), "focus-in-event",
+    g_signal_connect(w, "focus-in-event",
                      G_CALLBACK(entry_focus_in_callback), d->rule + i);
-    g_signal_connect(G_OBJECT(w), "changed", G_CALLBACK(entry_changed), d->rule + i);
-    g_signal_connect(G_OBJECT(w), "activate", G_CALLBACK(entry_activated), d->rule + i);
+    g_signal_connect(w, "changed", G_CALLBACK(entry_changed), d->rule + i);
+    g_signal_connect(w, "activate", G_CALLBACK(entry_activated), d->rule + i);
     gtk_entry_set_width_chars(GTK_ENTRY(w), 5);
 
     d->rule[i].button = w = dtgtk_button_new(dtgtk_cairo_paint_presets, 0, NULL);
     dt_gui_add_class(GTK_WIDGET(w), "dt_big_btn_canvas");
     gtk_widget_set_events(w, GDK_BUTTON_PRESS_MASK);
-    g_signal_connect(G_OBJECT(w), "button-press-event",
+    g_signal_connect(w, "button-press-event",
                      G_CALLBACK(popup_button_callback), d->rule + i);
 
     d->rule[i].hbox = dt_gui_hbox(d->rule[i].combo, dt_gui_expand(d->rule[i].text), d->rule[i].button);
@@ -3700,9 +3699,9 @@ void gui_init(dt_lib_module_t *self)
   d->view_rule = -1;
   d->view = view;
   gtk_tree_view_set_headers_visible(view, FALSE);
-  g_signal_connect(G_OBJECT(view), "button-press-event",
+  g_signal_connect(view, "button-press-event",
                    G_CALLBACK(view_onButtonPressed), d);
-  g_signal_connect(G_OBJECT(view), "popup-menu", G_CALLBACK(view_onPopupMenu), d);
+  g_signal_connect(view, "popup-menu", G_CALLBACK(view_onPopupMenu), d);
 
   GtkTreeViewColumn *col = gtk_tree_view_column_new();
   gtk_tree_view_append_column(view, col);
@@ -3765,13 +3764,13 @@ void gui_init(dt_lib_module_t *self)
 
 #ifdef _WIN32
   d->vmonitor = g_volume_monitor_get();
-  g_signal_connect(G_OBJECT(d->vmonitor), "mount-changed",
+  g_signal_connect(d->vmonitor, "mount-changed",
                    G_CALLBACK(_mount_changed), self);
-  g_signal_connect(G_OBJECT(d->vmonitor), "mount-added",
+  g_signal_connect(d->vmonitor, "mount-added",
                    G_CALLBACK(_mount_changed), self);
 #else
   d->vmonitor = g_unix_mount_monitor_get();
-  g_signal_connect(G_OBJECT(d->vmonitor), "mounts-changed",
+  g_signal_connect(d->vmonitor, "mounts-changed",
                    G_CALLBACK(_mount_changed), self);
 #endif
 
diff --git a/src/libs/colorpicker.c b/src/libs/colorpicker.c
index cb3faf4f2c87..71e36cbee0af 100644
--- a/src/libs/colorpicker.c
+++ b/src/libs/colorpicker.c
@@ -405,7 +405,7 @@ static gboolean _sample_tooltip_callback(GtkWidget *widget,
     view = gtk_text_view_new();
     dt_gui_add_class(view, "dt_transparent_background");
     dt_gui_add_class(view, "dt_monospace");
-    g_signal_connect(G_OBJECT(view), "destroy",
+    g_signal_connect(view, "destroy",
                      G_CALLBACK(gtk_widget_destroyed), &view);
   }
 
@@ -617,9 +617,9 @@ static void _add_sample(GtkButton *widget,
   sample->container = gtk_event_box_new();
   gtk_widget_add_events(sample->container,
                         GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
-  g_signal_connect(G_OBJECT(sample->container), "enter-notify-event",
+  g_signal_connect(sample->container, "enter-notify-event",
                    G_CALLBACK(_sample_enter_callback), sample);
-  g_signal_connect(G_OBJECT(sample->container), "leave-notify-event",
+  g_signal_connect(sample->container, "leave-notify-event",
                    G_CALLBACK(_sample_leave_callback), sample);
 
   sample->color_patch = gtk_drawing_area_new();
@@ -629,9 +629,9 @@ static void _add_sample(GtkButton *widget,
      _("hover to highlight sample on canvas,\n"
        "click to lock sample,\n"
        "right-click to load sample area into active color picker"));
-  g_signal_connect(G_OBJECT(sample->color_patch), "button-press-event",
+  g_signal_connect(sample->color_patch, "button-press-event",
                    G_CALLBACK(_live_sample_button), sample);
-  g_signal_connect(G_OBJECT(sample->color_patch), "draw",
+  g_signal_connect(sample->color_patch, "draw",
                    G_CALLBACK(_sample_draw_callback), sample);
 
   GtkWidget *color_patch_wrapper = dt_gui_hbox(dt_gui_expand(sample->color_patch));
@@ -642,13 +642,13 @@ static void _add_sample(GtkButton *widget,
   gtk_label_set_ellipsize(GTK_LABEL(sample->output_label), PANGO_ELLIPSIZE_START);
   gtk_label_set_selectable(GTK_LABEL(sample->output_label), TRUE);
   gtk_widget_set_has_tooltip(sample->output_label, TRUE);
-  g_signal_connect(G_OBJECT(sample->output_label), "query-tooltip",
+  g_signal_connect(sample->output_label, "query-tooltip",
                    G_CALLBACK(_sample_tooltip_callback), sample);
-  g_signal_connect(G_OBJECT(sample->output_label), "size-allocate",
+  g_signal_connect(sample->output_label, "size-allocate",
                    G_CALLBACK(_label_size_allocate_callback), sample);
 
   GtkWidget *delete_button = dtgtk_togglebutton_new(dtgtk_cairo_paint_remove, 0, NULL);
-  g_signal_connect(G_OBJECT(delete_button), "clicked",
+  g_signal_connect(delete_button, "clicked",
                    G_CALLBACK(_remove_sample_cb), sample);
 
   gtk_container_add(GTK_CONTAINER(sample->container),
@@ -734,13 +734,13 @@ void gui_init(dt_lib_module_t *self)
                         GDK_BUTTON_PRESS_MASK
                         | GDK_ENTER_NOTIFY_MASK
                         | GDK_LEAVE_NOTIFY_MASK);
-  g_signal_connect(G_OBJECT(color_patch), "draw",
+  g_signal_connect(color_patch, "draw",
                    G_CALLBACK(_sample_draw_callback), &data->primary_sample);
-  g_signal_connect(G_OBJECT(color_patch), "button-press-event",
+  g_signal_connect(color_patch, "button-press-event",
                    G_CALLBACK(_large_patch_toggle), data);
-  g_signal_connect(G_OBJECT(color_patch), "enter-notify-event",
+  g_signal_connect(color_patch, "enter-notify-event",
                    G_CALLBACK(_sample_enter_callback), &data->primary_sample);
-  g_signal_connect(G_OBJECT(color_patch), "leave-notify-event",
+  g_signal_connect(color_patch, "leave-notify-event",
                    G_CALLBACK(_sample_leave_callback), &data->primary_sample);
   GtkWidget *color_patch_wrapper = dt_gui_hbox(dt_gui_expand(color_patch));
   gtk_widget_set_name(GTK_WIDGET(color_patch_wrapper), "color-picker-area");
@@ -774,7 +774,7 @@ void gui_init(dt_lib_module_t *self)
     (data->picker_button,
      _("turn on color picker\nctrl+click or right-click to select an area"));
   gtk_widget_set_name(GTK_WIDGET(data->picker_button), "color-picker-button");
-  g_signal_connect(G_OBJECT(data->picker_button), "toggled",
+  g_signal_connect(data->picker_button, "toggled",
                    G_CALLBACK(_picker_button_toggled), data);
   dt_action_define(DT_ACTION(self), NULL, N_("pick color"),
                    data->picker_button, &dt_action_def_toggle);
@@ -782,17 +782,17 @@ void gui_init(dt_lib_module_t *self)
   // The small sample, label and add button
   GtkWidget *sample_row_events = gtk_event_box_new();
   gtk_widget_add_events(sample_row_events, GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
-  g_signal_connect(G_OBJECT(sample_row_events), "enter-notify-event",
+  g_signal_connect(sample_row_events, "enter-notify-event",
                    G_CALLBACK(_sample_enter_callback), &data->primary_sample);
-  g_signal_connect(G_OBJECT(sample_row_events), "leave-notify-event",
+  g_signal_connect(sample_row_events, "leave-notify-event",
                    G_CALLBACK(_sample_leave_callback), &data->primary_sample);
 
   data->primary_sample.color_patch = color_patch = gtk_drawing_area_new();
   gtk_widget_set_tooltip_text(color_patch, _("click to (un)hide large color patch"));
   gtk_widget_set_events(color_patch, GDK_BUTTON_PRESS_MASK);
-  g_signal_connect(G_OBJECT(color_patch), "button-press-event",
+  g_signal_connect(color_patch, "button-press-event",
                    G_CALLBACK(_large_patch_toggle), data);
-  g_signal_connect(G_OBJECT(color_patch), "draw",
+  g_signal_connect(color_patch, "draw",
                    G_CALLBACK(_sample_draw_callback), &data->primary_sample);
 
   GtkWidget *sample_patch_wrapper = dt_gui_hbox(dt_gui_expand(color_patch));
@@ -804,14 +804,14 @@ void gui_init(dt_lib_module_t *self)
   gtk_label_set_selectable(GTK_LABEL(label), TRUE);
   dt_gui_add_class(label, "dt_monospace");
   gtk_widget_set_has_tooltip(label, TRUE);
-  g_signal_connect(G_OBJECT(label), "query-tooltip",
+  g_signal_connect(label, "query-tooltip",
                    G_CALLBACK(_sample_tooltip_callback), &data->primary_sample);
-  g_signal_connect(G_OBJECT(label), "size-allocate",
+  g_signal_connect(label, "size-allocate",
                    G_CALLBACK(_label_size_allocate_callback), &data->primary_sample);
 
   data->add_sample_button = dtgtk_button_new(dtgtk_cairo_paint_square_plus, 0, NULL);
   gtk_widget_set_sensitive(data->add_sample_button, FALSE);
-  g_signal_connect(G_OBJECT(data->add_sample_button), "clicked",
+  g_signal_connect(data->add_sample_button, "clicked",
                    G_CALLBACK(_add_sample), self);
   dt_action_define(DT_ACTION(self), NULL, N_("add sample"),
                    data->add_sample_button, &dt_action_def_button);
@@ -832,7 +832,7 @@ void gui_init(dt_lib_module_t *self)
      PANGO_ELLIPSIZE_MIDDLE);
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(data->display_samples_check_box),
                                dt_conf_get_bool("ui_last/colorpicker_display_samples"));
-  g_signal_connect(G_OBJECT(data->display_samples_check_box), "toggled",
+  g_signal_connect(data->display_samples_check_box, "toggled",
                    G_CALLBACK(_display_samples_changed), NULL);
 
   GtkWidget *restrict_button =
@@ -845,7 +845,7 @@ void gui_init(dt_lib_module_t *self)
   gboolean restrict_histogram = dt_conf_get_bool("ui_last/colorpicker_restrict_histogram");
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(restrict_button), restrict_histogram);
   darktable.lib->proxy.colorpicker.restrict_histogram = restrict_histogram;
-  g_signal_connect(G_OBJECT(restrict_button), "toggled",
+  g_signal_connect(restrict_button, "toggled",
                    G_CALLBACK(_restrict_histogram_changed), NULL);
 
   // Setting up the GUI
diff --git a/src/libs/duplicate.c b/src/libs/duplicate.c
index cf6d5d190394..fe50641c50a5 100644
--- a/src/libs/duplicate.c
+++ b/src/libs/duplicate.c
@@ -124,7 +124,7 @@ static void _lib_duplicate_duplicate_clicked_callback(GtkWidget *widget,
   DT_CONTROL_SIGNAL_RAISE(DT_SIGNAL_VIEWMANAGER_THUMBTABLE_ACTIVATE, newid);
 }
 
-static void _lib_duplicate_delete(GtkButton *button, dt_lib_module_t *self)
+static void _lib_duplicate_delete(GtkWidget *button, dt_lib_module_t *self)
 {
   dt_lib_duplicate_t *d = self->data;
   const dt_imgid_t imgid = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(button), "imgid"));
@@ -157,9 +157,9 @@ static void _lib_duplicate_delete(GtkButton *button, dt_lib_module_t *self)
                              g_list_prepend(NULL, GINT_TO_POINTER(imgid)));
 }
 
-static void _lib_duplicate_thumb_press_callback(GtkWidget *widget,
-                                                GdkEventButton *event,
-                                                dt_lib_module_t *self)
+static gboolean _lib_duplicate_thumb_press_callback(GtkWidget *widget,
+                                                    GdkEventButton *event,
+                                                    dt_lib_module_t *self)
 {
   dt_lib_duplicate_t *d = self->data;
   dt_thumbnail_t *thumb = (dt_thumbnail_t *)g_object_get_data(G_OBJECT(widget), "thumb");
@@ -178,16 +178,18 @@ static void _lib_duplicate_thumb_press_callback(GtkWidget *widget,
       DT_CONTROL_SIGNAL_RAISE(DT_SIGNAL_VIEWMANAGER_THUMBTABLE_ACTIVATE, imgid);
     }
   }
+  return TRUE;
 }
 
-static void _lib_duplicate_thumb_release_callback(GtkWidget *widget,
-                                                  GdkEventButton *event,
-                                                  dt_lib_module_t *self)
+static gboolean _lib_duplicate_thumb_release_callback(GtkWidget *widget,
+                                                      GdkEventButton *event,
+                                                      dt_lib_module_t *self)
 {
   dt_lib_duplicate_t *d = self->data;
 
   d->imgid = NO_IMGID;
   dt_control_queue_redraw_center();
+  return TRUE;
 }
 
 void view_leave(struct dt_lib_module_t *self,
@@ -304,9 +306,9 @@ static void _lib_duplicate_init_callback(gpointer instance, dt_lib_module_t *sel
 
     if(imgid != dev->image_storage.id)
     {
-      g_signal_connect(G_OBJECT(thumb->w_main), "button-press-event",
+      g_signal_connect(thumb->w_main, "button-press-event",
                        G_CALLBACK(_lib_duplicate_thumb_press_callback), self);
-      g_signal_connect(G_OBJECT(thumb->w_main), "button-release-event",
+      g_signal_connect(thumb->w_main, "button-release-event",
                        G_CALLBACK(_lib_duplicate_thumb_release_callback), self);
     }
 
@@ -319,7 +321,7 @@ static void _lib_duplicate_init_callback(gpointer instance, dt_lib_module_t *sel
     gtk_widget_set_hexpand(tb, TRUE);
     g_object_set_data (G_OBJECT(tb), "imgid", GINT_TO_POINTER(imgid));
     gtk_widget_add_events(tb, GDK_FOCUS_CHANGE_MASK);
-    g_signal_connect(G_OBJECT(tb), "focus-out-event",
+    g_signal_connect(tb, "focus-out-event",
                      G_CALLBACK(_lib_duplicate_caption_out_callback), self);
     GtkWidget *lb = gtk_label_new (g_strdup(chl));
     gtk_widget_set_hexpand(lb, TRUE);
@@ -327,7 +329,7 @@ static void _lib_duplicate_init_callback(gpointer instance, dt_lib_module_t *sel
     gtk_widget_set_tooltip_text(bt, _("delete this duplicate"));
     //    gtk_widget_set_halign(bt, GTK_ALIGN_END);
     g_object_set_data(G_OBJECT(bt), "imgid", GINT_TO_POINTER(imgid));
-    g_signal_connect(G_OBJECT(bt), "clicked", G_CALLBACK(_lib_duplicate_delete), self);
+    g_signal_connect(bt, "clicked", G_CALLBACK(_lib_duplicate_delete), self);
 
     gtk_grid_attach(GTK_GRID(hb), thumb->w_main, 0, 0, 1, 2);
     gtk_grid_attach(GTK_GRID(hb), bt, 2, 0, 1, 1);
diff --git a/src/libs/export.c b/src/libs/export.c
index f0fde6b71cd0..e3e557b882f3 100644
--- a/src/libs/export.c
+++ b/src/libs/export.c
@@ -570,9 +570,9 @@ static gboolean _scale_mdlclick(GtkEntry *spin,
   return FALSE;
 }
 
-static void _widht_mdlclick(GtkEntry *spin,
-                            GdkEventButton *event,
-                            gpointer user_data)
+static gboolean _widht_mdlclick(GtkEntry *spin,
+                                GdkEventButton *event,
+                                gpointer user_data)
 {
   if(event->button == GDK_BUTTON_MIDDLE)
   {
@@ -585,11 +585,12 @@ static void _widht_mdlclick(GtkEntry *spin,
   {
     _width_changed(GTK_EDITABLE(spin), user_data);
   }
+  return TRUE;
 }
 
-static void _height_mdlclick(GtkEntry *spin,
-                             GdkEventButton *event,
-                             gpointer user_data)
+static gboolean _height_mdlclick(GtkEntry *spin,
+                                 GdkEventButton *event,
+                                 gpointer user_data)
 {
   if(event->button == GDK_BUTTON_MIDDLE)
   {
@@ -602,6 +603,7 @@ static void _height_mdlclick(GtkEntry *spin,
   {
     _height_changed(GTK_EDITABLE(spin), user_data);
   }
+  return TRUE;
 }
 
 static void _size_in_px_update(dt_lib_export_t *d)
@@ -1298,11 +1300,10 @@ static gboolean _batch_preset_active(dt_lib_module_t *self)
   return batch_preset_active;
 }
 
-static void _batch_export_toggled_callback(GtkCellRendererToggle *cell_renderer,
+static void _batch_export_toggled_callback(GtkCellRenderer *cell_renderer,
                                            gchar *path_str,
-                                           gpointer user_data)
+                                           dt_lib_module_t *self)
 {
-  dt_lib_module_t *self = user_data;
   dt_lib_export_t *d = self->data;
 
   GtkTreeModel *model = gtk_tree_view_get_model(GTK_TREE_VIEW(d->batch_treeview));
@@ -1413,7 +1414,7 @@ static void _export_presets_changed_callback(gpointer instance, gpointer module,
 void set_preferences(void *menu, dt_lib_module_t *self)
 {
   GtkWidget *mi = gtk_menu_item_new_with_label(_("preferences..."));
-  g_signal_connect(G_OBJECT(mi), "activate",
+  g_signal_connect(mi, "activate",
                    G_CALLBACK(_menuitem_preferences), self);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
@@ -1447,7 +1448,7 @@ void gui_init(dt_lib_module_t *self)
 
   // postponed so we can do the two steps in one loop
   DT_CONTROL_SIGNAL_HANDLE(DT_SIGNAL_IMAGEIO_STORAGE_CHANGE, _on_storage_list_changed);
-  g_signal_connect(G_OBJECT(d->storage), "value-changed",
+  g_signal_connect(d->storage, "value-changed",
                    G_CALLBACK(_storage_changed), self);
 
   d->format = dt_bauhaus_combobox_new_action(DT_ACTION(self));
@@ -1459,8 +1460,8 @@ void gui_init(dt_lib_module_t *self)
       "for these formats, no metadata fields will be included\n"
       "unless the user selects <b>all</b> of the metadata checkboxes in\n"
       "the export module preferences"));
-  g_signal_connect(G_OBJECT(d->format), "value-changed",
-                   G_CALLBACK(_format_changed), (gpointer)d);
+  g_signal_connect(d->format, "value-changed",
+                   G_CALLBACK(_format_changed), d);
 
   // add all format widgets to the stack widget
   d->format_extra_container = gtk_stack_new();
@@ -1640,7 +1641,7 @@ void gui_init(dt_lib_module_t *self)
 
   GtkWidget *styles_button = dtgtk_button_new(dtgtk_cairo_paint_styles, 0, NULL);
   gtk_widget_set_halign(styles_button,GTK_ALIGN_END);
-  g_signal_connect(G_OBJECT(styles_button), "clicked", G_CALLBACK(_style_popupmenu_callback), (gpointer)d);
+  g_signal_connect(styles_button, "clicked", G_CALLBACK(_style_popupmenu_callback), d);
   gtk_widget_set_tooltip_text(styles_button, _("select style to be applied on export"));
 //  dt_gui_add_help_link(styles, "bottom_panel_styles");
   GtkBox *style_box = (GtkBox*)gtk_box_new(GTK_ORIENTATION_HORIZONTAL,0);
@@ -1660,8 +1661,8 @@ void gui_init(dt_lib_module_t *self)
   _update_style_label(d, stored_style ? stored_style : "");
 
   //  Set callback signals
-  g_signal_connect(G_OBJECT(d->profile), "value-changed",
-                   G_CALLBACK(_profile_changed), (gpointer)d);
+  g_signal_connect(d->profile, "value-changed",
+                   G_CALLBACK(_profile_changed), d);
 
   // Export button
   d->export_button = GTK_BUTTON(dt_action_button_new
@@ -1729,16 +1730,16 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_add_events(d->print_height, GDK_BUTTON_PRESS_MASK);
   gtk_widget_add_events(d->scale, GDK_BUTTON_PRESS_MASK);
 
-  g_signal_connect(G_OBJECT(d->width), "button-press-event",
-                   G_CALLBACK(_widht_mdlclick), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->height), "button-press-event",
-                   G_CALLBACK(_height_mdlclick), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->print_width), "button-press-event",
-                   G_CALLBACK(_widht_mdlclick), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->print_height), "button-press-event",
-                   G_CALLBACK(_height_mdlclick), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->scale), "button-press-event",
-                   G_CALLBACK(_scale_mdlclick), (gpointer)d);
+  g_signal_connect(d->width, "button-press-event",
+                   G_CALLBACK(_widht_mdlclick), d);
+  g_signal_connect(d->height, "button-press-event",
+                   G_CALLBACK(_height_mdlclick), d);
+  g_signal_connect(d->print_width, "button-press-event",
+                   G_CALLBACK(_widht_mdlclick), d);
+  g_signal_connect(d->print_height, "button-press-event",
+                   G_CALLBACK(_height_mdlclick), d);
+  g_signal_connect(d->scale, "button-press-event",
+                   G_CALLBACK(_scale_mdlclick), d);
 
   // this takes care of keeping hidden widgets hidden
   gtk_widget_show_all(self->widget);
diff --git a/src/libs/export_metadata.c b/src/libs/export_metadata.c
index be126b1129e4..71e26281edba 100644
--- a/src/libs/export_metadata.c
+++ b/src/libs/export_metadata.c
@@ -195,7 +195,7 @@ char *dt_lib_export_metadata_configuration_dialog(char *metadata_presets, const
 
   GtkWidget *dttag = gtk_check_button_new_with_label(_("tags"));
   gtk_widget_set_tooltip_text(dttag, _("export tags (to Xmp.dc.Subject)"));
-  g_signal_connect(G_OBJECT(dttag), "clicked", G_CALLBACK(_tags_toggled), (gpointer)d);
+  g_signal_connect(dttag, "clicked", G_CALLBACK(_tags_toggled), (gpointer)d);
 
   d->private = gtk_check_button_new_with_label(_("private tags"));
   gtk_widget_set_tooltip_text(d->private, _("export private tags"));
@@ -220,7 +220,7 @@ char *dt_lib_export_metadata_configuration_dialog(char *metadata_presets, const
   gtk_tree_view_append_column(view, col);
   renderer = gtk_cell_renderer_text_new();
   g_object_set(renderer, "editable", TRUE, NULL);
-  g_signal_connect(G_OBJECT(renderer), "edited", G_CALLBACK(_formula_edited), (gpointer)d);
+  g_signal_connect(renderer, "edited", G_CALLBACK(_formula_edited), (gpointer)d);
   dt_gui_commit_on_focus_loss(renderer, &active_editable);
   col = gtk_tree_view_column_new_with_attributes(_("formula"), renderer, "text", 2, NULL);
   gtk_tree_view_append_column(view, col);
@@ -232,7 +232,7 @@ char *dt_lib_export_metadata_configuration_dialog(char *metadata_presets, const
                 "otherwise the corresponding metadata is calculated and added to exported file\n"
                 "click on formula cell to edit\n"
                 "type '$(' to activate the completion and see the list of variables"));
-  g_signal_connect(G_OBJECT(view), "key_press_event", G_CALLBACK(_key_press_on_list), (gpointer)d);
+  g_signal_connect(view, "key-press-event", G_CALLBACK(_key_press_on_list), (gpointer)d);
 
   GtkListStore *liststore = gtk_list_store_new(3, G_TYPE_STRING, G_TYPE_STRING, G_TYPE_STRING);
   d->liststore = liststore;
@@ -278,11 +278,11 @@ char *dt_lib_export_metadata_configuration_dialog(char *metadata_presets, const
 
   GtkWidget *plus = dtgtk_button_new(dtgtk_cairo_paint_plus_simple, 0, NULL);
   gtk_widget_set_tooltip_text(plus, _("add an output metadata tag"));
-  g_signal_connect(G_OBJECT(plus), "clicked", G_CALLBACK(_add_tag_button_clicked), (gpointer)d);
+  g_signal_connect(plus, "clicked", G_CALLBACK(_add_tag_button_clicked), (gpointer)d);
 
   GtkWidget *minus = dtgtk_button_new(dtgtk_cairo_paint_minus_simple, 0, NULL);
   gtk_widget_set_tooltip_text(minus, _("delete metadata tag"));
-  g_signal_connect(G_OBJECT(minus), "clicked", G_CALLBACK(_delete_tag_button_clicked), (gpointer)d);
+  g_signal_connect(minus, "clicked", G_CALLBACK(_delete_tag_button_clicked), (gpointer)d);
 
 #ifdef GDK_WINDOWING_QUARTZ
   dt_osx_disallow_fullscreen(dialog);
diff --git a/src/libs/filtering.c b/src/libs/filtering.c
index e6a9bfb5dafc..6ee8717dd406 100644
--- a/src/libs/filtering.c
+++ b/src/libs/filtering.c
@@ -736,7 +736,7 @@ static void _range_widget_add_to_rule(dt_lib_filtering_rule_t *rule, _widgets_ra
 
   gtk_box_pack_start(GTK_BOX((top) ? rule->w_special_box_top : rule->w_special_box), special->range_select, TRUE,
                      TRUE, 0);
-  g_signal_connect(G_OBJECT(special->range_select), "value-changed", G_CALLBACK(_range_changed), special);
+  g_signal_connect(special->range_select, "value-changed", G_CALLBACK(_range_changed), special);
   if(top)
   {
     dt_gui_add_class(gtk_bin_get_child(GTK_BIN(special->range_select)), "dt_quick_filter");
@@ -867,7 +867,7 @@ static void _popup_add_item(GtkMenuShell *pop, const gchar *name, const int id,
     g_object_set_data(G_OBJECT(smt), "collect_id", GINT_TO_POINTER(id));
     g_object_set_data(G_OBJECT(smt), "topbar", GINT_TO_POINTER(0));
     if(data) g_object_set_data(G_OBJECT(smt), "collect_data", data);
-    g_signal_connect(G_OBJECT(smt), "activate", callback, self);
+    g_signal_connect(smt, "activate", G_CALLBACK(callback), self);
   }
   gtk_menu_shell_append(pop, smt);
 }
@@ -1081,7 +1081,7 @@ static void _topbar_update(dt_lib_module_t *self)
         GtkWidget *evtb = gtk_event_box_new();
         GtkWidget *label = gtk_label_new(C_("quickfilter", "filter"));
         gtk_container_add(GTK_CONTAINER(evtb), label);
-        g_signal_connect(G_OBJECT(evtb), "button-press-event", G_CALLBACK(_topbar_label_press), self);
+        g_signal_connect(evtb, "button-press-event", G_CALLBACK(_topbar_label_press), self);
         gtk_box_pack_start(GTK_BOX(fbox), evtb, TRUE, TRUE, 0);
         gtk_widget_show_all(evtb);
       }
@@ -1253,7 +1253,7 @@ static gboolean _widget_init(dt_lib_filtering_rule_t *rule, const dt_collection_
     dt_bauhaus_combobox_set_selected_text_align(rule->w_operator, DT_BAUHAUS_COMBOBOX_ALIGN_LEFT);
     gtk_widget_set_tooltip_text(rule->w_operator, _("define how this rule should interact with the previous one"));
     gtk_box_pack_start(GTK_BOX(hbox), rule->w_operator, FALSE, FALSE, 0);
-    g_signal_connect(G_OBJECT(rule->w_operator), "value-changed", G_CALLBACK(_event_rule_changed), rule);
+    g_signal_connect(rule->w_operator, "value-changed", G_CALLBACK(_event_rule_changed), rule);
   }
 
   dt_bauhaus_combobox_set(rule->w_operator, mode);
@@ -1268,7 +1268,7 @@ static gboolean _widget_init(dt_lib_filtering_rule_t *rule, const dt_collection_
     _rule_populate_prop_combo(rule);
     g_object_set_data(G_OBJECT(rule->w_prop), "rule", rule);
     dt_bauhaus_combobox_set_from_value(rule->w_prop, prop);
-    g_signal_connect(G_OBJECT(rule->w_prop), "value-changed", G_CALLBACK(_event_rule_change_type), self);
+    g_signal_connect(rule->w_prop, "value-changed", G_CALLBACK(_event_rule_change_type), self);
     gtk_box_pack_start(GTK_BOX(hbox), rule->w_prop, TRUE, TRUE, 0);
   }
   else if(newprop)
@@ -1286,14 +1286,14 @@ static gboolean _widget_init(dt_lib_filtering_rule_t *rule, const dt_collection_
     rule->w_off = dtgtk_togglebutton_new(dtgtk_cairo_paint_switch, 0, NULL);
     dt_gui_add_class(rule->w_off, "dt_transparent_background");
     g_object_set_data(G_OBJECT(rule->w_off), "rule", rule);
-    g_signal_connect(G_OBJECT(rule->w_off), "toggled", G_CALLBACK(_event_rule_disable), rule);
+    g_signal_connect(rule->w_off, "toggled", G_CALLBACK(_event_rule_disable), rule);
     gtk_box_pack_end(GTK_BOX(rule->w_btn_box), rule->w_off, FALSE, FALSE, 0);
 
     // pin button
     rule->w_pin = dtgtk_togglebutton_new(dtgtk_cairo_paint_pin, 0, NULL);
     dt_gui_add_class(rule->w_pin, "dt_transparent_background");
     g_object_set_data(G_OBJECT(rule->w_pin), "rule", rule);
-    g_signal_connect(G_OBJECT(rule->w_pin), "toggled", G_CALLBACK(_rule_topbar_toggle), self);
+    g_signal_connect(rule->w_pin, "toggled", G_CALLBACK(_rule_topbar_toggle), self);
     dt_gui_add_class(rule->w_pin, "dt_dimmed");
     gtk_box_pack_end(GTK_BOX(rule->w_btn_box), rule->w_pin, FALSE, FALSE, 0);
     gtk_widget_set_no_show_all(rule->w_pin, TRUE);
@@ -1301,7 +1301,7 @@ static gboolean _widget_init(dt_lib_filtering_rule_t *rule, const dt_collection_
     // remove button
     rule->w_close = dtgtk_button_new(dtgtk_cairo_paint_remove, 0, NULL);
     g_object_set_data(G_OBJECT(rule->w_close), "rule", rule);
-    g_signal_connect(G_OBJECT(rule->w_close), "button-press-event", G_CALLBACK(_event_rule_close), self);
+    g_signal_connect(rule->w_close, "button-press-event", G_CALLBACK(_event_rule_close), self);
     gtk_box_pack_end(GTK_BOX(rule->w_btn_box), rule->w_close, FALSE, FALSE, 0);
   }
 
@@ -1569,7 +1569,7 @@ static void _event_history_show(GtkWidget *widget, dt_lib_module_t *self)
       GtkWidget *child = gtk_bin_get_child(GTK_BIN(smt));
       gtk_label_set_use_markup(GTK_LABEL(child), TRUE);
       g_object_set_data(G_OBJECT(smt), "history", GINT_TO_POINTER(i));
-      g_signal_connect(G_OBJECT(smt), "activate", G_CALLBACK(_event_history_apply), self);
+      g_signal_connect(smt, "activate", G_CALLBACK(_event_history_apply), self);
       gtk_menu_shell_append(pop, smt);
       g_free(line);
     }
@@ -1687,7 +1687,7 @@ static GtkWidget *_topbar_menu_new_rule(dt_lib_filtering_rule_t *rule, dt_lib_mo
   gtk_box_pack_start(GTK_BOX(hb), lb, TRUE, TRUE, 0);
   GtkWidget *btr = dtgtk_button_new(dtgtk_cairo_paint_remove, 0, NULL);
   g_object_set_data(G_OBJECT(btr), "rule", rule);
-  g_signal_connect(G_OBJECT(btr), "button-press-event", G_CALLBACK(_topbar_rule_remove), self);
+  g_signal_connect(btr, "button-press-event", G_CALLBACK(_topbar_rule_remove), self);
   gtk_box_pack_start(GTK_BOX(hb), btr, FALSE, TRUE, 0);
   return hb;
 }
@@ -1753,7 +1753,7 @@ static void _topbar_show_pref_menu(dt_lib_module_t *self, GtkWidget *bt)
   dt_bauhaus_combobox_mute_scrolling(nr);
   dt_bauhaus_widget_set_label(nr, NULL, _("new filter"));
   _topbar_populate_rules_combo(nr, d);
-  g_signal_connect(G_OBJECT(nr), "value-changed", G_CALLBACK(_topbar_rule_add), self);
+  g_signal_connect(nr, "value-changed", G_CALLBACK(_topbar_rule_add), self);
   gtk_box_pack_end(GTK_BOX(vbox2), nr, TRUE, TRUE, 0);
 
   gtk_box_pack_start(GTK_BOX(vbox), vbox2, TRUE, TRUE, 0);
@@ -1763,7 +1763,7 @@ static void _topbar_show_pref_menu(dt_lib_module_t *self, GtkWidget *bt)
   gtk_box_pack_start(GTK_BOX(vbox), lb, TRUE, TRUE, 0);
   GtkWidget *btr = gtk_button_new_with_label(_("reset quickfilters"));
   dt_gui_add_class(btr, "dt_transparent_background");
-  g_signal_connect(G_OBJECT(btr), "button-press-event", G_CALLBACK(_topbar_reset_press), self);
+  g_signal_connect(btr, "button-press-event", G_CALLBACK(_topbar_reset_press), self);
   gtk_box_pack_start(GTK_BOX(vbox), btr, TRUE, TRUE, 0);
 
   // show the popover
@@ -1938,7 +1938,7 @@ static gboolean _sort_init(_widgets_sort_t *sort, const dt_collection_sort_t sor
     dt_bauhaus_widget_hide_label(sort->sort);
     dt_bauhaus_combobox_mute_scrolling(sort->sort);
     gtk_widget_set_tooltip_text(sort->sort, _("determine the sort order of shown images"));
-    g_signal_connect(G_OBJECT(sort->sort), "value-changed", G_CALLBACK(_sort_combobox_changed), sort);
+    g_signal_connect(sort->sort, "value-changed", G_CALLBACK(_sort_combobox_changed), sort);
     gtk_box_pack_start(GTK_BOX(sort->box), sort->sort, TRUE, TRUE, 0);
 
     dt_bauhaus_combobox_add_section(sort->sort, _("files"));
@@ -1954,7 +1954,7 @@ static gboolean _sort_init(_widgets_sort_t *sort, const dt_collection_sort_t sor
     sort->direction = dtgtk_togglebutton_new(dtgtk_cairo_paint_sortby, CPF_DIRECTION_UP, NULL);
     gtk_widget_set_halign(sort->direction, GTK_ALIGN_START);
     gtk_box_pack_start(GTK_BOX(sort->box), sort->direction, FALSE, TRUE, 0);
-    g_signal_connect(G_OBJECT(sort->direction), "toggled", G_CALLBACK(_sort_reverse_changed), sort);
+    g_signal_connect(DTGTK_TOGGLEBUTTON(sort->direction), "toggled", G_CALLBACK(_sort_reverse_changed), sort);
     dt_gui_add_class(sort->direction, "dt_ignore_fg_state");
     if(num == 0)
       dt_action_define(DT_ACTION(self), NULL, _("sort direction"), sort->direction, &dt_action_def_toggle);
@@ -1963,7 +1963,7 @@ static gboolean _sort_init(_widgets_sort_t *sort, const dt_collection_sort_t sor
     gtk_widget_set_no_show_all(sort->close, TRUE);
     g_object_set_data(G_OBJECT(sort->close), "sort", sort);
     gtk_widget_set_tooltip_text(sort->close, _("remove this sort order"));
-    g_signal_connect(G_OBJECT(sort->close), "button-press-event", G_CALLBACK(_sort_close), self);
+    g_signal_connect(sort->close, "button-press-event", G_CALLBACK(_sort_close), self);
     gtk_box_pack_start(GTK_BOX(sort->box), sort->close, FALSE, FALSE, 0);
   }
 
@@ -2154,7 +2154,7 @@ static void _sort_history_show(GtkWidget *widget, dt_lib_module_t *self)
       GtkWidget *smt = gtk_menu_item_new_with_label(str);
       gtk_widget_set_tooltip_text(smt, str);
       g_object_set_data(G_OBJECT(smt), "history", GINT_TO_POINTER(i));
-      g_signal_connect(G_OBJECT(smt), "activate", G_CALLBACK(_sort_history_apply), self);
+      g_signal_connect(smt, "activate", G_CALLBACK(_sort_history_apply), self);
       gtk_menu_shell_append(pop, smt);
       g_free(line);
     }
diff --git a/src/libs/filters/colors.c b/src/libs/filters/colors.c
index b497d068befe..242bdb2ab7a7 100644
--- a/src/libs/filters/colors.c
+++ b/src/libs/filters/colors.c
@@ -295,8 +295,8 @@ static void _colors_widget_init(dt_lib_filtering_rule_t *rule, const dt_collecti
                                                      "\nclick to toggle the color label selection"
                                                      "\nctrl+click to exclude the color label"
                                                      "\nthe gray button affects all color labels"));
-    g_signal_connect(G_OBJECT(colors->colors[k]), "button-press-event", G_CALLBACK(_colors_clicked), colors);
-    g_signal_connect(G_OBJECT(colors->colors[k]), "enter-notify-event", G_CALLBACK(_colors_enter_notify),
+    g_signal_connect(colors->colors[k], "button-press-event", G_CALLBACK(_colors_clicked), colors);
+    g_signal_connect(colors->colors[k], "enter-notify-event", G_CALLBACK(_colors_enter_notify),
                      GINT_TO_POINTER(k));
     dt_action_define(DT_ACTION(self), N_("rules"), N_("color label"), colors->colors[k], &dt_action_def_colors_rule);
   }
@@ -306,8 +306,8 @@ static void _colors_widget_init(dt_lib_filtering_rule_t *rule, const dt_collecti
                               _("filter by images color label"
                                 "\nintersection: images having all selected color labels"
                                 "\nunion: images with at least one of the selected color labels"));
-  g_signal_connect(G_OBJECT(colors->operator), "clicked", G_CALLBACK(_colors_operator_clicked), colors);
-  g_signal_connect(G_OBJECT(colors->operator), "enter-notify-event", G_CALLBACK(_colors_enter_notify),
+  g_signal_connect(colors->operator, "clicked", G_CALLBACK(_colors_operator_clicked), colors);
+  g_signal_connect(colors->operator, "enter-notify-event", G_CALLBACK(_colors_enter_notify),
                    GINT_TO_POINTER(-1));
   dt_action_t *ac = dt_action_define(DT_ACTION(self), N_("rules"), N_("color label"), colors->operator, &dt_action_def_colors_rule);
 
diff --git a/src/libs/filters/filename.c b/src/libs/filters/filename.c
index 95a91cbae1e0..5601c598ab83 100644
--- a/src/libs/filters/filename.c
+++ b/src/libs/filters/filename.c
@@ -369,9 +369,9 @@ static void _filename_widget_init(dt_lib_filtering_rule_t *rule, const dt_collec
                                                 "multiple values can be separated by ','\n"
                                                 "\nright-click to get existing filenames"));
   gtk_box_pack_start(GTK_BOX(hb), filename->name, TRUE, TRUE, 0);
-  g_signal_connect(G_OBJECT(filename->name), "activate", G_CALLBACK(_filename_changed), filename);
-  g_signal_connect(G_OBJECT(filename->name), "focus-out-event", G_CALLBACK(_filename_focus_out), filename);
-  g_signal_connect(G_OBJECT(filename->name), "button-press-event", G_CALLBACK(_filename_press), filename);
+  g_signal_connect(filename->name, "activate", G_CALLBACK(_filename_changed), filename);
+  g_signal_connect(filename->name, "focus-out-event", G_CALLBACK(_filename_focus_out), filename);
+  g_signal_connect(filename->name, "button-press-event", G_CALLBACK(_filename_press), filename);
 
   filename->ext = dt_ui_entry_new(top ? 5 : 0);
   gtk_widget_set_can_default(filename->ext, TRUE);
@@ -381,9 +381,9 @@ static void _filename_widget_init(dt_lib_filtering_rule_t *rule, const dt_collec
                                                "handled keywords: 'RAW', 'NOT RAW', 'LDR', 'HDR'\n"
                                                "\nright-click to get existing extensions"));
   gtk_box_pack_start(GTK_BOX(hb), filename->ext, TRUE, TRUE, 0);
-  g_signal_connect(G_OBJECT(filename->ext), "activate", G_CALLBACK(_filename_changed), filename);
-  g_signal_connect(G_OBJECT(filename->ext), "focus-out-event", G_CALLBACK(_filename_focus_out), filename);
-  g_signal_connect(G_OBJECT(filename->ext), "button-press-event", G_CALLBACK(_filename_press), filename);
+  g_signal_connect(filename->ext, "activate", G_CALLBACK(_filename_changed), filename);
+  g_signal_connect(filename->ext, "focus-out-event", G_CALLBACK(_filename_focus_out), filename);
+  g_signal_connect(filename->ext, "button-press-event", G_CALLBACK(_filename_press), filename);
   if(top)
   {
     dt_gui_add_class(hb, "dt_quick_filter");
@@ -392,7 +392,7 @@ static void _filename_widget_init(dt_lib_filtering_rule_t *rule, const dt_collec
   // the popup
   filename->pop = gtk_popover_new(filename->name);
   gtk_widget_set_size_request(filename->pop, 250, 400);
-  g_signal_connect(G_OBJECT(filename->pop), "closed", G_CALLBACK(_filename_popup_closed), filename);
+  g_signal_connect(filename->pop, "closed", G_CALLBACK(_filename_popup_closed), filename);
   hb = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
   gtk_container_add(GTK_CONTAINER(filename->pop), hb);
 
@@ -406,9 +406,9 @@ static void _filename_widget_init(dt_lib_filtering_rule_t *rule, const dt_collec
   gtk_tree_view_set_headers_visible(GTK_TREE_VIEW(filename->name_tree), FALSE);
   GtkTreeSelection *sel = gtk_tree_view_get_selection(GTK_TREE_VIEW(filename->name_tree));
   gtk_tree_selection_set_mode(sel, GTK_SELECTION_MULTIPLE);
-  g_signal_connect(G_OBJECT(filename->name_tree), "row-activated", G_CALLBACK(_filename_tree_row_activated),
+  g_signal_connect(filename->name_tree, "row-activated", G_CALLBACK(_filename_tree_row_activated),
                    filename);
-  g_signal_connect(G_OBJECT(sel), "changed", G_CALLBACK(_filename_tree_selection_change), filename);
+  g_signal_connect(sel, "changed", G_CALLBACK(_filename_tree_selection_change), filename);
 
   GtkTreeViewColumn *col = gtk_tree_view_column_new();
   gtk_tree_view_append_column(GTK_TREE_VIEW(filename->name_tree), col);
@@ -432,9 +432,9 @@ static void _filename_widget_init(dt_lib_filtering_rule_t *rule, const dt_collec
   gtk_tree_view_set_headers_visible(GTK_TREE_VIEW(filename->ext_tree), FALSE);
   sel = gtk_tree_view_get_selection(GTK_TREE_VIEW(filename->ext_tree));
   gtk_tree_selection_set_mode(sel, GTK_SELECTION_MULTIPLE);
-  g_signal_connect(G_OBJECT(filename->name_tree), "row-activated", G_CALLBACK(_filename_tree_row_activated),
+  g_signal_connect(filename->name_tree, "row-activated", G_CALLBACK(_filename_tree_row_activated),
                    filename);
-  g_signal_connect(G_OBJECT(sel), "changed", G_CALLBACK(_filename_tree_selection_change), filename);
+  g_signal_connect(sel, "changed", G_CALLBACK(_filename_tree_selection_change), filename);
 
   col = gtk_tree_view_column_new();
   gtk_tree_view_append_column(GTK_TREE_VIEW(filename->ext_tree), col);
@@ -451,7 +451,7 @@ static void _filename_widget_init(dt_lib_filtering_rule_t *rule, const dt_collec
   // the button to close the popup
   GtkWidget *btn = gtk_button_new_with_label(_("ok"));
   gtk_box_pack_start(GTK_BOX(hb), btn, FALSE, TRUE, 0);
-  g_signal_connect(G_OBJECT(btn), "clicked", G_CALLBACK(_filename_ok_clicked), filename);
+  g_signal_connect(btn, "clicked", G_CALLBACK(_filename_ok_clicked), filename);
 
   if(top)
     rule->w_specific_top = filename;
diff --git a/src/libs/filters/misc.c b/src/libs/filters/misc.c
index 2b6172bc932d..f56e13d0a628 100644
--- a/src/libs/filters/misc.c
+++ b/src/libs/filters/misc.c
@@ -457,9 +457,9 @@ static void _misc_widget_init(dt_lib_filtering_rule_t *rule,
   g_free(name);
 
   gtk_box_pack_start(GTK_BOX(hb), misc->name, TRUE, TRUE, 0);
-  g_signal_connect(G_OBJECT(misc->name), "activate", G_CALLBACK(_misc_changed), misc);
-  g_signal_connect(G_OBJECT(misc->name), "focus-out-event", G_CALLBACK(_misc_focus_out), misc);
-  g_signal_connect(G_OBJECT(misc->name), "button-press-event", G_CALLBACK(_misc_press), misc);
+  g_signal_connect(misc->name, "activate", G_CALLBACK(_misc_changed), misc);
+  g_signal_connect(misc->name, "focus-out-event", G_CALLBACK(_misc_focus_out), misc);
+  g_signal_connect(misc->name, "button-press-event", G_CALLBACK(_misc_press), misc);
 
   if(top)
   {
@@ -469,7 +469,7 @@ static void _misc_widget_init(dt_lib_filtering_rule_t *rule,
   // the popup
   misc->pop = gtk_popover_new(misc->name);
   gtk_widget_set_size_request(misc->pop, 250, 400);
-  g_signal_connect(G_OBJECT(misc->pop), "closed", G_CALLBACK(_misc_popup_closed), misc);
+  g_signal_connect(misc->pop, "closed", G_CALLBACK(_misc_popup_closed), misc);
   hb = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
   gtk_container_add(GTK_CONTAINER(misc->pop), hb);
 
@@ -483,8 +483,8 @@ static void _misc_widget_init(dt_lib_filtering_rule_t *rule,
   gtk_tree_view_set_headers_visible(GTK_TREE_VIEW(misc->name_tree), FALSE);
   GtkTreeSelection *sel = gtk_tree_view_get_selection(GTK_TREE_VIEW(misc->name_tree));
   gtk_tree_selection_set_mode(sel, GTK_SELECTION_MULTIPLE);
-  g_signal_connect(G_OBJECT(misc->name_tree), "row-activated", G_CALLBACK(_misc_tree_row_activated), misc);
-  g_signal_connect(G_OBJECT(sel), "changed", G_CALLBACK(_misc_tree_selection_changed), misc);
+  g_signal_connect(misc->name_tree, "row-activated", G_CALLBACK(_misc_tree_row_activated), misc);
+  g_signal_connect(sel, "changed", G_CALLBACK(_misc_tree_selection_changed), misc);
 
   GtkTreeViewColumn *col = gtk_tree_view_column_new();
   gtk_tree_view_append_column(GTK_TREE_VIEW(misc->name_tree), col);
@@ -500,7 +500,7 @@ static void _misc_widget_init(dt_lib_filtering_rule_t *rule,
   // the button to close the popup
   GtkWidget *btn = gtk_button_new_with_label(_("ok"));
   gtk_box_pack_start(GTK_BOX(hb), btn, FALSE, TRUE, 0);
-  g_signal_connect(G_OBJECT(btn), "clicked", G_CALLBACK(_misc_ok_clicked), misc);
+  g_signal_connect(btn, "clicked", G_CALLBACK(_misc_ok_clicked), misc);
 
   if(top)
     rule->w_specific_top = misc;
diff --git a/src/libs/filters/search.c b/src/libs/filters/search.c
index 8139f554d5d8..578d27bfeb85 100644
--- a/src/libs/filters/search.c
+++ b/src/libs/filters/search.c
@@ -170,8 +170,8 @@ static void _search_widget_init(dt_lib_filtering_rule_t *rule, const dt_collecti
     gtk_box_pack_start(GTK_BOX(rule->w_special_box), hbox, TRUE, TRUE, 0);
   search->text = gtk_search_entry_new();
   gtk_drag_dest_unset(search->text);
-  g_signal_connect(G_OBJECT(search->text), "search-changed", G_CALLBACK(_search_changed), search);
-  g_signal_connect(G_OBJECT(search->text), "stop-search", G_CALLBACK(_search_reset_text_entry), rule);
+  g_signal_connect(search->text, "search-changed", G_CALLBACK(_search_changed), search);
+  g_signal_connect(search->text, "stop-search", G_CALLBACK(_search_reset_text_entry), rule);
   if(top)
     gtk_entry_set_max_width_chars(GTK_ENTRY(search->text), 20);
   gtk_entry_set_width_chars(GTK_ENTRY(search->text), 0);
diff --git a/src/libs/geotagging.c b/src/libs/geotagging.c
index 7234fd2bd697..86ceb1d99991 100644
--- a/src/libs/geotagging.c
+++ b/src/libs/geotagging.c
@@ -570,7 +570,7 @@ static gboolean _click_for_entire_track(GtkEntry *spin, GdkEventButton *event, d
   return FALSE;
 }
 
-static void _track_seg_toggled(GtkCellRendererToggle *cell_renderer, gchar *path_str, dt_lib_module_t *self)
+static void _track_seg_toggled(GtkCellRenderer *cell_renderer, gchar *path_str, dt_lib_module_t *self)
 {
   dt_lib_geotagging_t *d = self->data;
   GtkTreeModel *model = gtk_tree_view_get_model(GTK_TREE_VIEW(d->map.gpx_view));
@@ -1795,7 +1795,7 @@ void gui_init(dt_lib_module_t *self)
   d->lock_offset = dtgtk_togglebutton_new(dtgtk_cairo_paint_lock, 0, NULL);
   gtk_widget_set_tooltip_text(d->lock_offset, _("lock date/time offset value to apply it onto another selection"));
   gtk_widget_set_halign(d->lock_offset, GTK_ALIGN_START);
-  g_signal_connect(G_OBJECT(d->lock_offset), "clicked", G_CALLBACK(_toggle_lock_button_callback), (gpointer)self);
+  g_signal_connect(d->lock_offset, "clicked", G_CALLBACK(_toggle_lock_button_callback), self);
 
   box = _gui_init_datetime(_("date/time offset"), &d->of, 2, self, group, d->lock_offset,
                            _("offset or difference ([-]dd hh:mm:ss[.sss])"));
@@ -1853,8 +1853,8 @@ void gui_init(dt_lib_module_t *self)
   gtk_entry_completion_set_match_func(completion, _completion_match_func, NULL, NULL);
   gtk_entry_completion_set_minimum_key_length(completion, 0);
   gtk_entry_set_completion(GTK_ENTRY(d->timezone), completion);
-  g_signal_connect(G_OBJECT(d->timezone), "key-press-event", G_CALLBACK(_timezone_key_pressed), self);
-  g_signal_connect(G_OBJECT(d->timezone), "focus-out-event", G_CALLBACK(_timezone_focus_out), self);
+  g_signal_connect(d->timezone, "key-press-event", G_CALLBACK(_timezone_key_pressed), self);
+  g_signal_connect(d->timezone, "focus-out-event", G_CALLBACK(_timezone_focus_out), self);
 
   // gpx
   d->gpx_button = dt_action_button_new(self, N_("apply GPX track file..."), _choose_gpx_callback, self,
@@ -1878,7 +1878,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_name(d->map.gpx_button, "non-flat");
   gtk_widget_set_tooltip_text(d->map.gpx_button, _("select a GPX track file..."));
   gtk_grid_attach(grid, d->map.gpx_button, 0, line, 1, 1);
-  g_signal_connect(G_OBJECT(d->map.gpx_button), "clicked", G_CALLBACK(_choose_gpx_callback), self);
+  g_signal_connect(d->map.gpx_button, "clicked", G_CALLBACK(_choose_gpx_callback), self);
 
   d->map.gpx_file = dt_ui_label_new("");
   gtk_label_set_ellipsize(GTK_LABEL(d->map.gpx_file ), PANGO_ELLIPSIZE_MIDDLE);
@@ -1919,8 +1919,8 @@ void gui_init(dt_lib_module_t *self)
   gtk_tree_view_append_column(GTK_TREE_VIEW(d->map.gpx_view), column);
 
   g_object_set(G_OBJECT(d->map.gpx_view), "has-tooltip", TRUE, NULL);
-  g_signal_connect(G_OBJECT(d->map.gpx_view), "query-tooltip", G_CALLBACK(_row_tooltip_setup), self);
-  g_signal_connect(G_OBJECT(d->map.gpx_view), "button-press-event", G_CALLBACK(_click_for_entire_track), self);
+  g_signal_connect(d->map.gpx_view, "query-tooltip", G_CALLBACK(_row_tooltip_setup), self);
+  g_signal_connect(d->map.gpx_view, "button-press-event", G_CALLBACK(_click_for_entire_track), self);
 
   // avoid ugly console pixman messages due to headers
   gtk_tree_view_set_headers_visible(GTK_TREE_VIEW(d->map.gpx_view), FALSE);
diff --git a/src/libs/histogram.c b/src/libs/histogram.c
index 72ce7f1e0efb..555d04704b47 100644
--- a/src/libs/histogram.c
+++ b/src/libs/histogram.c
@@ -2151,11 +2151,10 @@ static gboolean _color_harmony_clicked(GtkWidget *button,
   return TRUE;
 }
 
-static gboolean _color_harmony_enter_notify_callback(const GtkWidget *widget,
+static gboolean _color_harmony_enter_notify_callback(GtkWidget *widget,
                                                      GdkEventCrossing *event,
-                                                     const gpointer user_data)
+                                                     dt_lib_histogram_t *d)
 {
-  dt_lib_histogram_t *d = (dt_lib_histogram_t *)user_data;
   // find positions of entered button
 
   d->color_harmony_old = d->harmony_guide.type;
@@ -2173,9 +2172,8 @@ static gboolean _color_harmony_enter_notify_callback(const GtkWidget *widget,
 
 static gboolean _color_harmony_leave_notify_callback(GtkWidget *widget,
                                                      GdkEventCrossing *event,
-                                                     const gpointer user_data)
+                                                     dt_lib_histogram_t *d)
 {
-  dt_lib_histogram_t *d = (dt_lib_histogram_t *)user_data;
   d->harmony_guide.type = d->color_harmony_old;
   gtk_widget_queue_draw(d->scope_draw);
   return FALSE;
@@ -2584,7 +2582,7 @@ void gui_init(dt_lib_module_t *self)
     dt_action_define(dark, N_("modes"), dt_lib_histogram_scope_type_names[i],
                      d->scope_type_button[i], &dt_action_def_toggle);
     gtk_box_pack_start(GTK_BOX(box_left), d->scope_type_button[i], FALSE, FALSE, 0);
-    g_signal_connect(G_OBJECT(d->scope_type_button[i]), "button-press-event",
+    g_signal_connect(d->scope_type_button[i], "button-press-event",
                      G_CALLBACK(_scope_histogram_mode_clicked), d);
   }
   gtk_toggle_button_set_active
@@ -2649,11 +2647,11 @@ void gui_init(dt_lib_module_t *self)
                                            &(dt_color_harmonies[i]));
     dt_action_define(dark, N_("color harmonies"),
                      dt_color_harmonies[i].name, rb, &dt_action_def_toggle);
-    g_signal_connect(G_OBJECT(rb), "button-press-event",
+    g_signal_connect(rb, "button-press-event",
                      G_CALLBACK(_color_harmony_clicked), d);
-    g_signal_connect(G_OBJECT(rb), "enter-notify-event",
+    g_signal_connect(rb, "enter-notify-event",
                      G_CALLBACK(_color_harmony_enter_notify_callback), d);
-    g_signal_connect(G_OBJECT(rb), "leave-notify-event",
+    g_signal_connect(rb, "leave-notify-event",
                      G_CALLBACK(_color_harmony_leave_notify_callback), d);
 
     gtk_box_pack_start(GTK_BOX(d->color_harmony_box), rb, FALSE, FALSE, 0);
@@ -2701,22 +2699,22 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_name(self->widget, "main-histogram");
 
   /* connect callbacks */
-  g_signal_connect(G_OBJECT(d->scope_view_button), "clicked",
+  g_signal_connect(d->scope_view_button, "clicked",
                    G_CALLBACK(_scope_view_clicked), d);
-  g_signal_connect(G_OBJECT(d->colorspace_button), "clicked",
+  g_signal_connect(d->colorspace_button, "clicked",
                    G_CALLBACK(_colorspace_clicked), d);
 
-  g_signal_connect(G_OBJECT(d->red_channel_button), "toggled",
+  g_signal_connect(d->red_channel_button, "toggled",
                    G_CALLBACK(_red_channel_toggle), d);
-  g_signal_connect(G_OBJECT(d->green_channel_button), "toggled",
+  g_signal_connect(d->green_channel_button, "toggled",
                    G_CALLBACK(_green_channel_toggle), d);
-  g_signal_connect(G_OBJECT(d->blue_channel_button), "toggled",
+  g_signal_connect(d->blue_channel_button, "toggled",
                    G_CALLBACK(_blue_channel_toggle), d);
 
   gtk_widget_add_events(d->scope_draw, GDK_LEAVE_NOTIFY_MASK | GDK_POINTER_MOTION_MASK
                                      | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
   // FIXME: why does cursor motion over buttons trigger multiple draw callbacks?
-  g_signal_connect(G_OBJECT(d->scope_draw), "draw", G_CALLBACK(_drawable_draw_callback), d);
+  g_signal_connect(d->scope_draw, "draw", G_CALLBACK(_drawable_draw_callback), d);
   dt_gui_connect_click_all(d->scope_draw, _drawable_button_press,
                                           _drawable_button_release, d);
   dt_gui_connect_motion(d->scope_draw, _drawable_motion, NULL,
@@ -2726,13 +2724,13 @@ void gui_init(dt_lib_module_t *self)
     (eventbox,
      GDK_LEAVE_NOTIFY_MASK | GDK_ENTER_NOTIFY_MASK
      | GDK_POINTER_MOTION_MASK | darktable.gui->scroll_mask);
-  g_signal_connect(G_OBJECT(eventbox), "scroll-event",
+  g_signal_connect(eventbox, "scroll-event",
                    G_CALLBACK(_eventbox_scroll_callback), d);
-  g_signal_connect(G_OBJECT(eventbox), "enter-notify-event",
+  g_signal_connect(eventbox, "enter-notify-event",
                    G_CALLBACK(_eventbox_enter_notify_callback), d);
-  g_signal_connect(G_OBJECT(eventbox), "leave-notify-event",
+  g_signal_connect(eventbox, "leave-notify-event",
                    G_CALLBACK(_eventbox_leave_notify_callback), d);
-  g_signal_connect(G_OBJECT(eventbox), "motion-notify-event",
+  g_signal_connect(eventbox, "motion-notify-event",
                    G_CALLBACK(_eventbox_motion_notify_callback), d);
 
   gtk_widget_show_all(self->widget);
diff --git a/src/libs/history.c b/src/libs/history.c
index 94e343064582..8114049447a4 100644
--- a/src/libs/history.c
+++ b/src/libs/history.c
@@ -140,12 +140,12 @@ void gui_init(dt_lib_module_t *self)
     (self, N_("compress history stack"), _lib_history_compress_clicked_callback, self,
      _("create a minimal history stack which produces the same image\n"
        "ctrl+click to truncate history to the selected item"), 0, 0);
-  g_signal_connect(G_OBJECT(d->compress_button), "button-press-event",
+  g_signal_connect(d->compress_button, "button-press-event",
                    G_CALLBACK(_lib_history_compress_pressed_callback), self);
 
   /* add toolbar button for creating style */
   d->create_button = dtgtk_button_new(dtgtk_cairo_paint_styles, CPF_NONE, NULL);
-  g_signal_connect(G_OBJECT(d->create_button), "clicked",
+  g_signal_connect(d->create_button, "clicked",
                    G_CALLBACK(_lib_history_create_style_button_clicked_callback), NULL);
   gtk_widget_set_name(d->create_button, "non-flat");
   gtk_widget_set_tooltip_text(d->create_button,
@@ -236,7 +236,7 @@ static GtkWidget *_lib_history_create_button(dt_lib_module_t *self,
   if(selected) gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(widget), TRUE);
 
   /* set callback when clicked */
-  g_signal_connect(G_OBJECT(widget), "button-press-event",
+  g_signal_connect(widget, "button-press-event",
                    G_CALLBACK(_lib_history_button_clicked_callback), self);
 
   /* associate the history number */
@@ -881,7 +881,7 @@ static gboolean _changes_tooltip_callback(GtkWidget *widget,
                                           const gint y,
                                           const gboolean keyboard_mode,
                                           GtkTooltip *tooltip,
-                                          const dt_dev_history_item_t *hitem)
+                                          dt_dev_history_item_t *hitem)
 {
   dt_iop_params_t *old_params = hitem->module->default_params;
   dt_develop_blend_params_t *old_blend = hitem->module->default_blendop_params;
@@ -1039,7 +1039,7 @@ static gboolean _changes_tooltip_callback(GtkWidget *widget,
       view = gtk_text_view_new();
       dt_gui_add_class(view, "dt_transparent_background");
       dt_gui_add_class(view, "dt_monospace");
-      g_signal_connect(G_OBJECT(view), "destroy", G_CALLBACK(gtk_widget_destroyed), &view);
+      g_signal_connect(view, "destroy", G_CALLBACK(gtk_widget_destroyed), &view);
     }
 
     // find tabs to align columns and decimals
@@ -1150,7 +1150,7 @@ void gui_update(dt_lib_module_t *self)
       history;
       history = g_list_next(history))
   {
-    const dt_dev_history_item_t *hitem = history->data;
+    dt_dev_history_item_t *hitem = history->data;
     gchar *label = _lib_history_button_label(hitem);
 
     const gboolean selected = (num == darktable.develop->history_end - 1);
@@ -1164,8 +1164,8 @@ void gui_update(dt_lib_module_t *self)
     g_free(label);
 
     gtk_widget_set_has_tooltip(widget, TRUE);
-    g_signal_connect(G_OBJECT(widget), "query-tooltip",
-                     G_CALLBACK(_changes_tooltip_callback), (void *)hitem);
+    g_signal_connect(widget, "query-tooltip",
+                     G_CALLBACK(_changes_tooltip_callback), hitem);
 
     gtk_box_pack_end(GTK_BOX(d->history_box), widget, FALSE, FALSE, 0);
     num++;
diff --git a/src/libs/image.c b/src/libs/image.c
index 01276b1b49b3..f32473ecd2aa 100644
--- a/src/libs/image.c
+++ b/src/libs/image.c
@@ -550,7 +550,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_text(d->rotate_ccw_button,
                               _("rotate selected images 90 degrees CCW"));
   gtk_grid_attach(grid, d->rotate_ccw_button, 0, line, 1, 1);
-  g_signal_connect(G_OBJECT(d->rotate_ccw_button), "clicked",
+  g_signal_connect(d->rotate_ccw_button, "clicked",
                    G_CALLBACK(button_clicked), GINT_TO_POINTER(4));
   dt_action_define(DT_ACTION(self), NULL,
                    N_("rotate selected images 90 degrees CCW"),
@@ -561,7 +561,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_text(d->rotate_cw_button,
                               _("rotate selected images 90 degrees CW"));
   gtk_grid_attach(grid, d->rotate_cw_button, 1, line, 1, 1);
-  g_signal_connect(G_OBJECT(d->rotate_cw_button), "clicked",
+  g_signal_connect(d->rotate_cw_button, "clicked",
                    G_CALLBACK(button_clicked), GINT_TO_POINTER(5));
   dt_action_define(DT_ACTION(self), NULL,
                    N_("rotate selected images 90 degrees CW"),
@@ -614,7 +614,7 @@ void gui_init(dt_lib_module_t *self)
     dt_conf_get_bool("plugins/lighttable/copy_metadata/" #item)); \
   dt_action_define(DT_ACTION(meta), N_("flags"),                  \
                    label, flag, &dt_action_def_toggle);           \
-  g_signal_connect(G_OBJECT(flag), "clicked",                     \
+  g_signal_connect(flag, "clicked",                     \
                    G_CALLBACK(_##item##_flag_callback), self); }
 
   META_FLAG_BUTTON(N_("ratings"),  rating,   0, _("select ratings metadata"));
@@ -628,7 +628,7 @@ void gui_init(dt_lib_module_t *self)
      _copy_metadata_callback, self,
      _("set the selected image as source of metadata"), 0, 0);
   gtk_grid_attach(grid, d->copy_metadata_button, 0, ++line, 2, 1);
-  g_signal_connect(G_OBJECT(d->copy_metadata_button), "clicked",
+  g_signal_connect(d->copy_metadata_button, "clicked",
                    G_CALLBACK(_copy_metadata_callback), self);
 
   d->paste_metadata_button = dt_action_button_new
@@ -762,8 +762,8 @@ static int lua_register_action(lua_State *L)
   lua_callback_data * data = malloc(sizeof(lua_callback_data));
   data->key = strdup(name);
   data->self = self;
-  const gulong s = g_signal_connect(G_OBJECT(button), "clicked",
-                                    G_CALLBACK(lua_button_clicked), data);
+  const gulong s = g_signal_connect_data(button, "clicked",
+                                         G_CALLBACK(lua_button_clicked), data, NULL, 0);
 
   // save the signal connection in case we need to destroy it later
   dt_lua_module_entry_push(L, "lib", self->plugin_name);
diff --git a/src/libs/import.c b/src/libs/import.c
index b9fa2566fa56..255652393e86 100644
--- a/src/libs/import.c
+++ b/src/libs/import.c
@@ -299,7 +299,7 @@ void _lib_import_ui_devices_update(dt_lib_module_t *self)
                                 PANGO_ELLIPSIZE_END);
         d->import_camera = GTK_BUTTON(ib);
         d->camera = camera;
-        g_signal_connect(G_OBJECT(ib), "clicked",
+        g_signal_connect(ib, "clicked",
                          G_CALLBACK(_lib_import_from_camera_callback), self);
         gtk_widget_set_halign(gtk_bin_get_child(GTK_BIN(ib)), GTK_ALIGN_CENTER);
         dt_gui_add_help_link(ib, "import_camera");
@@ -310,7 +310,7 @@ void _lib_import_ui_devices_update(dt_lib_module_t *self)
                            (tb = gtk_button_new_with_label(_("tethered shoot"))),
                            FALSE, FALSE, 0);
         d->tethered_shoot = GTK_BUTTON(tb);
-        g_signal_connect(G_OBJECT(tb), "clicked",
+        g_signal_connect(tb, "clicked",
                          G_CALLBACK(_lib_import_tethered_callback), camera);
         gtk_widget_set_halign(gtk_bin_get_child(GTK_BIN(tb)), GTK_ALIGN_CENTER);
         dt_gui_add_help_link(tb, "import_camera");
@@ -320,7 +320,7 @@ void _lib_import_ui_devices_update(dt_lib_module_t *self)
                          (um = gtk_button_new_with_label(_("unmount camera"))),
                          FALSE, FALSE, 0);
       d->unmount_camera = GTK_BUTTON(um);
-      g_signal_connect(G_OBJECT(um), "clicked",
+      g_signal_connect(um, "clicked",
                        G_CALLBACK(_lib_import_unmount_callback), camera);
       gtk_widget_set_halign(gtk_bin_get_child(GTK_BIN(um)), GTK_ALIGN_CENTER);
       dt_gui_add_help_link(um, "mount_camera");
@@ -357,7 +357,7 @@ void _lib_import_ui_devices_update(dt_lib_module_t *self)
                               PANGO_ELLIPSIZE_END);
       d->mount_camera = GTK_BUTTON(im);
 
-      g_signal_connect(G_OBJECT(im), "clicked",
+      g_signal_connect(im, "clicked",
                        G_CALLBACK(_lib_import_mount_callback), camera);
       gtk_widget_set_halign(gtk_bin_get_child(GTK_BIN(im)), GTK_ALIGN_CENTER);
       dt_gui_add_help_link(im, "mount_camera");
@@ -1494,7 +1494,7 @@ static void _set_places_list(GtkWidget *places_paned,
   gtk_paned_pack1(GTK_PANED(places_paned), places_top_box, TRUE, TRUE);
 
 
-  g_signal_connect(G_OBJECT(d->placesView), "button-press-event",
+  g_signal_connect(d->placesView, "button-press-event",
                    G_CALLBACK(_places_button_press), self);
 }
 
@@ -1519,7 +1519,7 @@ static void _set_folders_list(GtkWidget *places_paned, dt_lib_module_t* self)
   gtk_tree_view_column_set_resizable(column, TRUE);
   gtk_tree_view_set_expander_column(d->from.folderview, column);
   g_signal_connect(d->from.folderview, "row-expanded", G_CALLBACK(_row_expanded), self);
-  g_signal_connect(G_OBJECT(d->from.folderview), "button-press-event",
+  g_signal_connect(d->from.folderview, "button-press-event",
                    G_CALLBACK(_folders_button_press), self);
   gtk_tree_view_column_set_sort_column_id(column, DT_FOLDER_PATH);
   gtk_tree_sortable_set_sort_column_id(GTK_TREE_SORTABLE(store), DT_FOLDER_PATH,
@@ -1930,12 +1930,12 @@ static void _set_files_list(GtkWidget *rbox, dt_lib_module_t* self)
   gtk_tree_view_column_set_clickable(column, TRUE);
   gtk_tree_view_column_set_min_width(column, DT_PIXEL_APPLY_DPI(128));
   d->from.pixcol = column;
-  g_signal_connect(G_OBJECT(d->from.treeview), "button-press-event",
+  g_signal_connect(d->from.treeview, "button-press-event",
                    G_CALLBACK(_files_button_press), self);
 
   GtkTreeSelection *selection = gtk_tree_view_get_selection(d->from.treeview);
   gtk_tree_selection_set_mode(selection, GTK_SELECTION_MULTIPLE);
-  g_signal_connect(G_OBJECT(selection), "changed",
+  g_signal_connect(selection, "changed",
                    G_CALLBACK(_import_from_selection_changed), self);
 
   gtk_tree_view_set_model(d->from.treeview, GTK_TREE_MODEL(d->from.store));
@@ -2015,7 +2015,7 @@ static void _set_expander_content(GtkWidget *rbox,
   gtk_widget_set_tooltip_text(browsedir, _("select directory"));
 
   gtk_box_pack_start(GTK_BOX(hbox), browsedir, FALSE, FALSE, 0);
-  g_signal_connect(G_OBJECT(browsedir), "clicked", G_CALLBACK(_browse_basedir_clicked),
+  g_signal_connect(browsedir, "clicked", G_CALLBACK(_browse_basedir_clicked),
                    basedir);
   gtk_grid_attach_next_to(grid, hbox, gtk_grid_get_child_at(grid, 0, line - 1),
                           GTK_POS_RIGHT, 1, 1);
@@ -2105,7 +2105,7 @@ static void _import_from_dialog_new(dt_lib_module_t* self)
   d->import_new = dt_gui_preferences_bool(grid, "ui_last/import_select_new", col++,
                                           line, TRUE);
   gtk_widget_set_hexpand(gtk_grid_get_child_at(grid, col++, line), TRUE);
-  g_signal_connect(G_OBJECT(d->import_new), "toggled",
+  g_signal_connect(d->import_new, "toggled",
                    G_CALLBACK(_import_new_toggled), self);
 
   if(d->import_case != DT_IMPORT_CAMERA)
@@ -2113,13 +2113,13 @@ static void _import_from_dialog_new(dt_lib_module_t* self)
     d->recursive = dt_gui_preferences_bool(grid, "ui_last/import_recursive", col++,
                                            line, TRUE);
     gtk_widget_set_hexpand(gtk_grid_get_child_at(grid, col++, line), TRUE);
-    g_signal_connect(G_OBJECT(d->recursive), "toggled",
+    g_signal_connect(d->recursive, "toggled",
                      G_CALLBACK(_recursive_toggled), self);
   }
   GtkWidget *ignore_nonraws =
     dt_gui_preferences_bool(grid, "ui_last/import_ignore_nonraws", col++, line, TRUE);
   gtk_widget_set_hexpand(gtk_grid_get_child_at(grid, col++, line++), TRUE);
-  g_signal_connect(G_OBJECT(ignore_nonraws), "toggled",
+  g_signal_connect(ignore_nonraws, "toggled",
                    G_CALLBACK(_ignore_nonraws_toggled), self);
   gtk_box_pack_start(GTK_BOX(rbox), GTK_WIDGET(grid), FALSE, FALSE, 8);
 
diff --git a/src/libs/lib.c b/src/libs/lib.c
index 8be7b42ceb08..1ee551ae24f3 100644
--- a/src/libs/lib.c
+++ b/src/libs/lib.c
@@ -438,7 +438,7 @@ static void dt_lib_presets_popup_menu_show(dt_lib_module_info_t *minfo,
   const gboolean hide_default = dt_conf_get_bool("plugins/lighttable/hide_default_presets");
   const gboolean default_first = dt_conf_get_bool("modules/default_presets_first");
 
-  g_signal_connect(G_OBJECT(menu), "destroy", G_CALLBACK(free_module_info), minfo);
+  g_signal_connect(menu, "destroy", G_CALLBACK(free_module_info), minfo);
 
   GtkWidget *mi;
   int active_preset = -1, cnt = 0;
@@ -517,9 +517,9 @@ static void dt_lib_presets_popup_menu_show(dt_lib_module_info_t *minfo,
     g_object_set_data(G_OBJECT(mi), "dt-preset-module", minfo->module);
     dt_action_define(&minfo->module->actions, "preset", name, mi, NULL);
 
-    g_signal_connect(G_OBJECT(mi), "activate",
+    g_signal_connect(mi, "activate",
                      G_CALLBACK(_menuitem_activate_preset), minfo);
-    g_signal_connect(G_OBJECT(mi), "button-release-event",
+    g_signal_connect(GTK_MENU_ITEM(mi), "button-release-event",
                      G_CALLBACK(_menuitem_button_preset), minfo);
     gtk_widget_set_tooltip_text(mi, (const char *)sqlite3_column_text(stmt, 3));
     gtk_widget_set_has_tooltip(mi, TRUE);
@@ -536,7 +536,7 @@ static void dt_lib_presets_popup_menu_show(dt_lib_module_info_t *minfo,
   if(minfo->module->manage_presets)
   {
     mi = gtk_menu_item_new_with_label(_("manage presets..."));
-    g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(menuitem_manage_presets), minfo);
+    g_signal_connect(mi, "activate", G_CALLBACK(menuitem_manage_presets), minfo);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
     cnt++;
   }
@@ -545,11 +545,11 @@ static void dt_lib_presets_popup_menu_show(dt_lib_module_info_t *minfo,
     if(!selected_writeprotect)
     {
       mi = gtk_menu_item_new_with_label(_("edit this preset.."));
-      g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(menuitem_edit_preset), minfo);
+      g_signal_connect(mi, "activate", G_CALLBACK(menuitem_edit_preset), minfo);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
       mi = gtk_menu_item_new_with_label(_("delete this preset"));
-      g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(menuitem_delete_preset), minfo);
+      g_signal_connect(mi, "activate", G_CALLBACK(menuitem_delete_preset), minfo);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
       cnt++;
     }
@@ -563,7 +563,7 @@ static void dt_lib_presets_popup_menu_show(dt_lib_module_info_t *minfo,
       gtk_widget_set_tooltip_text(mi, _("nothing to save"));
     }
     else
-      g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(menuitem_new_preset), minfo);
+      g_signal_connect(mi, "activate", G_CALLBACK(menuitem_new_preset), minfo);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 
     if(darktable.gui->last_preset && found)
@@ -578,7 +578,7 @@ static void dt_lib_presets_popup_menu_show(dt_lib_module_info_t *minfo,
       gtk_label_set_markup(GTK_LABEL(gtk_bin_get_child(GTK_BIN(mi))), markup);
       g_object_set_data_full(G_OBJECT(mi), "dt-preset-name",
                              g_strdup(darktable.gui->last_preset), g_free);
-      g_signal_connect(G_OBJECT(mi), "activate",
+      g_signal_connect(mi, "activate",
                        G_CALLBACK(menuitem_update_preset), minfo);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
       g_free(markup);
@@ -845,7 +845,7 @@ void dt_lib_init_presets(dt_lib_module_t *module)
 }
 
 static gboolean _lib_draw_callback(GtkWidget *widget,
-                                   gpointer cr,
+                                   cairo_t *cr,
                                    dt_lib_module_t *self)
 {
   dt_lib_gui_update(self);
@@ -883,7 +883,7 @@ static void dt_lib_init_module(void *m)
     {
       g_object_ref_sink(module->widget);
       if(module->gui_update)
-        g_signal_connect(G_OBJECT(module->widget), "draw",
+        g_signal_connect(module->widget, "draw",
                          G_CALLBACK(_lib_draw_callback), module);
     }
   }
@@ -895,16 +895,15 @@ void _lib_unload_module(dt_lib_module_t *module)
     g_module_close(module->module);
 }
 
-static gboolean _lib_gui_reset_callback(GtkButton *button,
+static gboolean _lib_gui_reset_callback(GtkWidget *button,
                                         GdkEventButton *e,
-                                        gpointer user_data)
+                                        dt_lib_module_t *module)
 {
-  dt_lib_module_t *module = (dt_lib_module_t *)user_data;
   module->gui_reset(module);
   return TRUE;
 }
 
-static gboolean _presets_popup_callback(GtkButton *button,
+static gboolean _presets_popup_callback(GtkWidget *button,
                                         GdkEventButton *e,
                                         dt_lib_module_t *module)
 {
@@ -921,7 +920,7 @@ static gboolean _presets_popup_callback(GtkButton *button,
     //         mi->params, mi->params_size);
     mi->params_size = 0;
   }
-  dt_lib_presets_popup_menu_show(mi, GTK_WIDGET(button));
+  dt_lib_presets_popup_menu_show(mi, button);
 
   if(button)
     dtgtk_button_set_active(DTGTK_BUTTON(button), FALSE);
@@ -968,12 +967,10 @@ gboolean dt_lib_gui_get_expanded(dt_lib_module_t *module)
 
 static gboolean _lib_plugin_arrow_button_press(GtkWidget *w,
                                                GdkEventButton *e,
-                                               gpointer user_data)
+                                               dt_lib_module_t *module)
 {
   if(e->type == GDK_2BUTTON_PRESS || e->type == GDK_3BUTTON_PRESS) return TRUE;
 
-  dt_lib_module_t *module = (dt_lib_module_t *)user_data;
-
   if(e->button == GDK_BUTTON_PRIMARY)
   {
     /* bail out if module is static */
@@ -1033,10 +1030,10 @@ static gboolean _lib_plugin_arrow_button_press(GtkWidget *w,
 
 static gboolean _lib_plugin_header_button_release(GtkWidget *w,
                                                   GdkEventButton *e,
-                                                  gpointer user_data)
+                                                  dt_lib_module_t *module)
 {
   if(GTK_IS_BUTTON(gtk_get_event_widget((GdkEvent*)e))) return FALSE;
-  return _lib_plugin_arrow_button_press(w, e, user_data);
+  return _lib_plugin_arrow_button_press(w, e, module);
 }
 
 static void show_module_callback(dt_lib_module_t *module)
@@ -1086,19 +1083,21 @@ static gboolean _header_enter_notify_callback(GtkWidget *eventbox,
 }
 
 static gboolean _body_enter_leave_callback(GtkWidget *widget,
-                                            GdkEventCrossing *e,
-                                            gpointer user_data)
+                                           GdkEventCrossing *e,
+                                           dt_lib_module_t *module)
 {
   // set or clear focused module when entering or leaving (not when opening popup)
   if(e->detail != GDK_NOTIFY_INFERIOR && e->mode == GDK_CROSSING_NORMAL)
-    darktable.lib->gui_module = e->type == GDK_ENTER_NOTIFY ? user_data : NULL;
+    darktable.lib->gui_module = e->type == GDK_ENTER_NOTIFY ? module : NULL;
 
   return FALSE;
 }
 
 static gboolean _on_drag_motion(GtkWidget *widget,
                                 GdkDragContext *dc,
-                                gint x, gint y, guint time,
+                                const gint x,
+                                const gint y,
+                                const guint time,
                                 dt_lib_module_t *dest)
 {
   dt_lib_module_t *src = NULL;
@@ -1215,7 +1214,7 @@ GtkWidget *dt_lib_gui_get_expander(dt_lib_module_t *module)
       // FIXME separately define as darkroom widget shortcut/action,
       // because not automatically registered via lib if presets btn
       // has been loaded to be shown outside expander
-      g_signal_connect(G_OBJECT(module->presets_button), "button-press-event",
+      g_signal_connect(module->presets_button, "button-press-event",
                        G_CALLBACK(_presets_popup_callback), module);
     }
     module->expander = NULL;
@@ -1242,17 +1241,17 @@ GtkWidget *dt_lib_gui_get_expander(dt_lib_module_t *module)
   }
 
   /* setup the header box */
-  g_signal_connect(G_OBJECT(header_evb), "button-release-event",
+  g_signal_connect(header_evb, "button-release-event",
                    G_CALLBACK(_lib_plugin_header_button_release),
                    module);
-  g_signal_connect(G_OBJECT(header_evb), "enter-notify-event",
+  g_signal_connect(header_evb, "enter-notify-event",
                    G_CALLBACK(_header_enter_notify_callback),
                    GINT_TO_POINTER(DT_ACTION_ELEMENT_SHOW));
 
   /* (un)focus module when entering/leaving body */
-  g_signal_connect(G_OBJECT(body_evb), "enter-notify-event",
+  g_signal_connect(body_evb, "enter-notify-event",
                    G_CALLBACK(_body_enter_leave_callback), module);
-  g_signal_connect(G_OBJECT(body_evb), "leave-notify-event",
+  g_signal_connect(body_evb, "leave-notify-event",
                    G_CALLBACK(_body_enter_leave_callback), module);
 
   /*
@@ -1262,7 +1261,7 @@ GtkWidget *dt_lib_gui_get_expander(dt_lib_module_t *module)
   module->arrow = dtgtk_button_new(dtgtk_cairo_paint_solid_arrow, 0, NULL);
 
   gtk_widget_set_tooltip_text(module->arrow, _("show module"));
-  g_signal_connect(G_OBJECT(module->arrow), "button-press-event",
+  g_signal_connect(module->arrow, "button-press-event",
                     G_CALLBACK(_lib_plugin_arrow_button_press), module);
   dt_action_define(&module->actions, NULL, NULL, module->arrow, NULL);
   gtk_box_pack_start(GTK_BOX(header), module->arrow, FALSE, FALSE, 0);
@@ -1287,9 +1286,9 @@ GtkWidget *dt_lib_gui_get_expander(dt_lib_module_t *module)
   /* add preset button if module has implementation */
   module->presets_button = dtgtk_button_new(dtgtk_cairo_paint_presets, 0, NULL);
   gtk_widget_set_tooltip_text(module->presets_button, _("presets and preferences"));
-  g_signal_connect(G_OBJECT(module->presets_button), "button-press-event",
+  g_signal_connect(module->presets_button, "button-press-event",
                    G_CALLBACK(_presets_popup_callback), module);
-  g_signal_connect(G_OBJECT(module->presets_button), "enter-notify-event",
+  g_signal_connect(module->presets_button, "enter-notify-event",
                    G_CALLBACK(_header_enter_notify_callback),
                    GINT_TO_POINTER(DT_ACTION_ELEMENT_PRESETS));
   if(!module->get_params
@@ -1301,9 +1300,9 @@ GtkWidget *dt_lib_gui_get_expander(dt_lib_module_t *module)
 
   /* add reset button if module has implementation */
   module->reset_button = dtgtk_button_new(dtgtk_cairo_paint_reset, 0, NULL);
-  g_signal_connect(G_OBJECT(module->reset_button), "button-press-event",
+  g_signal_connect(module->reset_button, "button-press-event",
                    G_CALLBACK(_lib_gui_reset_callback), module);
-  g_signal_connect(G_OBJECT(module->reset_button), "enter-notify-event",
+  g_signal_connect(module->reset_button, "enter-notify-event",
                    G_CALLBACK(_header_enter_notify_callback),
                    GINT_TO_POINTER(DT_ACTION_ELEMENT_RESET));
   if(!module->gui_reset) gtk_widget_set_sensitive(module->reset_button, FALSE);
diff --git a/src/libs/live_view.c b/src/libs/live_view.c
index a9f7dbd31c15..da6b9a0570e6 100644
--- a/src/libs/live_view.c
+++ b/src/libs/live_view.c
@@ -318,7 +318,7 @@ void gui_init(dt_lib_module_t *self)
   button = dtgtk_##type##button_new(paint, direction, NULL);                 \
   gtk_widget_set_tooltip_text(button, action);                               \
   gtk_box_pack_start(GTK_BOX(box), button, TRUE, TRUE, 0);                   \
-  g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(callback), data); \
+  g_signal_connect(button, "clicked", G_CALLBACK(callback), data); \
   dt_action_define(DT_ACTION(self), NULL, action, button, *(#type)?&dt_action_def_toggle:&dt_action_def_button);
 
   lib->live_view = NEW_BUTTON(toggle, dtgtk_cairo_paint_eye, 0,
@@ -370,7 +370,7 @@ void gui_init(dt_lib_module_t *self)
   dt_bauhaus_combobox_add(lib->overlay, _("selected image"));
   dt_bauhaus_combobox_add(lib->overlay, _("id"));
   gtk_widget_set_tooltip_text(lib->overlay, _("overlay another image over the live view"));
-  g_signal_connect(G_OBJECT(lib->overlay), "value-changed",
+  g_signal_connect(lib->overlay, "value-changed",
                    G_CALLBACK(overlay_changed), lib);
   gtk_box_pack_start(GTK_BOX(self->widget), lib->overlay, TRUE, TRUE, 0);
 
@@ -381,7 +381,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_spin_button_set_digits(GTK_SPIN_BUTTON(lib->overlay_id), 0);
   gtk_widget_set_tooltip_text(lib->overlay_id,
                               _("enter image id of the overlay manually"));
-  g_signal_connect(G_OBJECT(lib->overlay_id), "value-changed",
+  g_signal_connect(lib->overlay_id, "value-changed",
                    G_CALLBACK(_overlay_id_changed), lib);
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(lib->overlay_id),
                             dt_conf_get_int("plugins/lighttable/live_view/overlay_imgid"));
@@ -415,7 +415,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_text(lib->overlay_mode, _("mode of the overlay"));
   dt_bauhaus_combobox_set(lib->overlay_mode,
                           dt_conf_get_int("plugins/lighttable/live_view/overlay_mode"));
-  g_signal_connect(G_OBJECT(lib->overlay_mode), "value-changed",
+  g_signal_connect(lib->overlay_mode, "value-changed",
                    G_CALLBACK(_overlay_mode_changed), lib);
   gtk_box_pack_start(GTK_BOX(self->widget), lib->overlay_mode, TRUE, TRUE, 0);
 
@@ -426,7 +426,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_text(lib->overlay_splitline, _("only draw part of the overlay"));
   dt_bauhaus_combobox_set(lib->overlay_splitline,
                           dt_conf_get_int("plugins/lighttable/live_view/splitline"));
-  g_signal_connect(G_OBJECT(lib->overlay_splitline), "value-changed",
+  g_signal_connect(lib->overlay_splitline, "value-changed",
                    G_CALLBACK(_overlay_splitline_changed),
                    lib);
   gtk_box_pack_start(GTK_BOX(self->widget), lib->overlay_splitline, TRUE, TRUE, 0);
diff --git a/src/libs/location.c b/src/libs/location.c
index 5be0ce9f8af0..051133c8f6cc 100644
--- a/src/libs/location.c
+++ b/src/libs/location.c
@@ -140,9 +140,9 @@ void gui_init(dt_lib_module_t *self)
 
   /* add search box */
   lib->search = GTK_ENTRY(dt_ui_entry_new(0));
-  g_signal_connect(G_OBJECT(lib->search), "activate",
+  g_signal_connect(lib->search, "activate",
                    G_CALLBACK(_lib_location_entry_activated),
-                   (gpointer)self);
+                   self);
 
   /* add result vbox */
   lib->result = dt_gui_vbox();
@@ -173,9 +173,9 @@ static GtkWidget *_lib_location_place_widget_new(dt_lib_location_t *lib,
   GtkWidget *eb, *vb, *w;
   eb = gtk_event_box_new();
   gtk_widget_set_name(eb, "dt-map-location");
-  g_signal_connect(G_OBJECT(eb), "enter-notify-event",
+  g_signal_connect(eb, "enter-notify-event",
                    G_CALLBACK(_event_box_enter_leave), NULL);
-  g_signal_connect(G_OBJECT(eb), "leave-notify-event",
+  g_signal_connect(eb, "leave-notify-event",
                    G_CALLBACK(_event_box_enter_leave), NULL);
 
   vb = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
@@ -211,7 +211,7 @@ static GtkWidget *_lib_location_place_widget_new(dt_lib_location_t *lib,
     lib->callback_params = g_list_append(lib->callback_params, param);
     param->lib = lib;
     param->result = place;
-    g_signal_connect(G_OBJECT(eb), "button-press-event",
+    g_signal_connect(eb, "button-press-event",
                      G_CALLBACK(_lib_location_result_item_activated),
                      (gpointer)param);
   }
diff --git a/src/libs/map_locations.c b/src/libs/map_locations.c
index f7d5952ae4b0..1e523369d001 100644
--- a/src/libs/map_locations.c
+++ b/src/libs/map_locations.c
@@ -622,7 +622,7 @@ static void _name_start_editing(GtkCellRenderer *renderer, GtkCellEditable *edit
     }
     gtk_tree_path_free(new_path);
 
-    g_signal_connect(G_OBJECT(editable), "editing-done", G_CALLBACK(_name_editing_done), self);
+    g_signal_connect(editable, "editing-done", G_CALLBACK(_name_editing_done), self);
   }
 }
 
@@ -774,10 +774,10 @@ static void _pop_menu_view(GtkWidget *view, GdkEventButton *event, dt_lib_module
     const gboolean children = gtk_tree_model_iter_children(model, &child, &parent);
 
     menuitem = gtk_menu_item_new_with_label(_("edit location"));
-    g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_edit_location, self);
+    g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_edit_location), self);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
     menuitem = gtk_menu_item_new_with_label(_("delete location"));
-    g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_delete_location, self);
+    g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_delete_location), self);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
     if(children)
     {
@@ -792,10 +792,10 @@ static void _pop_menu_view(GtkWidget *view, GdkEventButton *event, dt_lib_module
     {
       gtk_widget_set_sensitive(menuitem, FALSE);
     }
-    g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_update_filmstrip, self);
+    g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_update_filmstrip), self);
     menuitem = gtk_menu_item_new_with_label(_("go to collection (lighttable)"));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
-    g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_goto_collection, self);
+    g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_goto_collection), self);
     if(!locid)
     {
       gtk_widget_set_sensitive(menuitem, FALSE);
@@ -912,7 +912,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_tree_view_column_add_attribute(col, renderer, "text", DT_MAP_LOCATION_COL_TAG);
   gtk_tree_view_column_set_cell_data_func(col, renderer, _tree_name_show, (gpointer)self, NULL);
 //  g_object_set(renderer, "editable", TRUE, NULL);
-  g_signal_connect(G_OBJECT(renderer), "editing-started", G_CALLBACK(_name_start_editing), self);
+  g_signal_connect(renderer, "editing-started", G_CALLBACK(_name_start_editing), self);
   d->renderer = renderer;
 
   GtkTreeSelection *selection = gtk_tree_view_get_selection(view);
@@ -920,7 +920,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_tree_selection_set_mode(selection, GTK_SELECTION_SINGLE);
   gtk_tree_view_set_model(view, GTK_TREE_MODEL(treestore));
   g_object_unref(treestore);
-  g_signal_connect(G_OBJECT(view), "button-press-event", G_CALLBACK(_click_on_view), self);
+  g_signal_connect(view, "button-press-event", G_CALLBACK(_click_on_view), self);
   gtk_widget_set_tooltip_text(GTK_WIDGET(view),
                               _("list of user locations,"
                                 "\nclick to show or hide a location on the map:"
@@ -945,8 +945,8 @@ void gui_init(dt_lib_module_t *self)
   }
   d->shape_button = dtgtk_togglebutton_new(location_shapes[shape], 0, NULL);
   gtk_box_pack_start(hbox, d->shape_button, FALSE, TRUE, 0);
-  d->shape_button_handler = g_signal_connect(G_OBJECT(d->shape_button), "clicked",
-                                             G_CALLBACK(_shape_button_clicked), self);
+  d->shape_button_handler = g_signal_connect_data(d->shape_button, "clicked",
+                                                  G_CALLBACK(_shape_button_clicked), self, NULL, 0);
   gtk_widget_set_tooltip_text(GTK_WIDGET(d->shape_button ),
                               _("select the shape of the location\'s limits on the map, circle or rectangle"
                                 "\nor even polygon if available (select first a polygon place in 'find location' module)"));
@@ -961,14 +961,14 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_text(d->show_all_button,
                               _("show all locations which are on the visible map"));
   gtk_box_pack_end(hbox, d->show_all_button, FALSE, FALSE, 8);
-  g_signal_connect(G_OBJECT(d->show_all_button), "clicked", G_CALLBACK(_show_all_button_clicked), self);
+  g_signal_connect(d->show_all_button, "clicked", G_CALLBACK(_show_all_button_clicked), self);
 
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(hbox), FALSE, TRUE, 0);
 
   _locations_tree_update(self,0);
   _display_buttons(self);
 
-  g_signal_connect(G_OBJECT(selection), "changed", G_CALLBACK(_selection_changed), self);
+  g_signal_connect(selection, "changed", G_CALLBACK(_selection_changed), self);
 
   // connect geotag changed signal
   DT_CONTROL_SIGNAL_HANDLE(DT_SIGNAL_GEOTAG_CHANGED, _view_map_geotag_changed);
diff --git a/src/libs/map_settings.c b/src/libs/map_settings.c
index dd6115424497..2ff72879d955 100644
--- a/src/libs/map_settings.c
+++ b/src/libs/map_settings.c
@@ -104,7 +104,7 @@ void gui_init(dt_lib_module_t *self)
     }
   }
   dt_bauhaus_combobox_set(d->map_source_dropdown, selection);
-  g_signal_connect(G_OBJECT(d->map_source_dropdown), "value-changed", G_CALLBACK(_map_source_changed), NULL);
+  g_signal_connect(d->map_source_dropdown, "value-changed", G_CALLBACK(_map_source_changed), NULL);
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(d->map_source_dropdown), FALSE, TRUE, 0);
 
   GtkGrid *grid = GTK_GRID(gtk_grid_new());
@@ -113,25 +113,25 @@ void gui_init(dt_lib_module_t *self)
   int line = 0;
   d->max_outline_nodes = dt_gui_preferences_int(grid, "plugins/map/max_outline_nodes", 0, line++);
   d->show_osd_checkbutton = dt_gui_preferences_bool(grid, "plugins/map/show_map_osd", 0, line++, FALSE);
-  g_signal_connect(G_OBJECT(d->show_osd_checkbutton), "toggled", G_CALLBACK(_show_osd_toggled), NULL);
+  g_signal_connect(d->show_osd_checkbutton, "toggled", G_CALLBACK(_show_osd_toggled), NULL);
   d->filtered_images_checkbutton = dt_gui_preferences_bool(grid, "plugins/map/filter_images_drawn", 0, line++, FALSE);
-  g_signal_connect(G_OBJECT(d->filtered_images_checkbutton), "toggled", G_CALLBACK(_parameter_changed), NULL);
+  g_signal_connect(d->filtered_images_checkbutton, "toggled", G_CALLBACK(_parameter_changed), NULL);
   dt_shortcut_register(dt_action_define(DT_ACTION(self), NULL, N_("filtered images"),
                                         d->filtered_images_checkbutton, &dt_action_def_button),
                        0, 0, GDK_KEY_s, GDK_CONTROL_MASK);
   d->max_images_entry = dt_gui_preferences_int(grid, "plugins/map/max_images_drawn", 0, line++);
-  g_signal_connect(G_OBJECT(d->max_images_entry), "value-changed", G_CALLBACK(_parameter_changed), self);
+  g_signal_connect(d->max_images_entry, "value-changed", G_CALLBACK(_parameter_changed), self);
   d->epsilon_factor = dt_gui_preferences_int(grid, "plugins/map/epsilon_factor", 0, line++);
-  g_signal_connect(G_OBJECT(d->epsilon_factor), "value-changed", G_CALLBACK(_parameter_changed), self);
+  g_signal_connect(d->epsilon_factor, "value-changed", G_CALLBACK(_parameter_changed), self);
   d->min_images = dt_gui_preferences_int(grid, "plugins/map/min_images_per_group", 0, line++);
-  g_signal_connect(G_OBJECT(d->min_images), "value-changed", G_CALLBACK(_parameter_changed), self);
+  g_signal_connect(d->min_images, "value-changed", G_CALLBACK(_parameter_changed), self);
 
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(grid), FALSE, TRUE, 0);
 
   d->images_thumb = dt_gui_preferences_enum(DT_ACTION(self), "plugins/map/images_thumbnail");
   dt_action_t *ac = dt_bauhaus_widget_set_label(d->images_thumb, NULL, dt_confgen_get_label("plugins/map/images_thumbnail"));
   dt_shortcut_register(ac, 0, 0, GDK_KEY_s, GDK_SHIFT_MASK);
-  g_signal_connect(G_OBJECT(d->images_thumb), "value-changed", G_CALLBACK(_parameter_changed), self);
+  g_signal_connect(d->images_thumb, "value-changed", G_CALLBACK(_parameter_changed), self);
   gtk_box_pack_start(GTK_BOX(self->widget), d->images_thumb, FALSE, TRUE, 0);
 }
 
diff --git a/src/libs/masks.c b/src/libs/masks.c
index 2e02dae44bb7..45c418902a6d 100644
--- a/src/libs/masks.c
+++ b/src/libs/masks.c
@@ -120,8 +120,9 @@ gboolean _timeout_show_all_feathers(gpointer userdata)
   return G_SOURCE_REMOVE;
 }
 
-static void _property_changed(GtkWidget *widget, dt_masks_property_t prop)
+static void _property_changed(GtkWidget *widget, gpointer user_data)
 {
+  dt_masks_property_t prop = (dt_masks_property_t)GPOINTER_TO_INT(user_data);
   dt_lib_module_t *self = darktable.develop->proxy.masks.module;
   dt_lib_masks_t *d = self->data;
   dt_develop_t *dev = darktable.develop;
@@ -250,7 +251,7 @@ static void _update_all_properties(dt_lib_masks_t *self)
   gtk_widget_show(self->none_label);
 
   for(int i = 0; i < DT_MASKS_PROPERTY_LAST; i++)
-    _property_changed(self->property[i], i);
+    _property_changed(self->property[i], GINT_TO_POINTER(i));
 
   dt_masks_form_t *form = darktable.develop->form_visible;
   gboolean drawing_brush = form && form->type & DT_MASKS_BRUSH;
@@ -309,9 +310,9 @@ static void _tree_add_shape(GtkButton *button, gpointer shape)
   dt_control_queue_redraw_center();
 }
 
-static void _bt_add_shape(GtkWidget *widget, GdkEventButton *event, gpointer shape)
+static gboolean _bt_add_shape(GtkWidget *widget, GdkEventButton *event, gpointer shape)
 {
-  if(darktable.gui->reset) return;
+  if(darktable.gui->reset) return FALSE;
 
   if(event->button == GDK_BUTTON_PRIMARY)
   {
@@ -326,6 +327,7 @@ static void _bt_add_shape(GtkWidget *widget, GdkEventButton *event, gpointer sha
 
     _lib_masks_inactivate_icons(darktable.develop->proxy.masks.module);
   }
+  return TRUE;
 }
 
 static void _tree_add_exist(GtkButton *button, dt_masks_form_t *grp)
@@ -524,7 +526,7 @@ static void _add_tree_operation(GtkMenuShell *menu,
   gtk_widget_set_sensitive(item, sensitive);
   if(selected_states & state)
     gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(item), TRUE);
-  g_signal_connect(item, "activate", (GCallback)_tree_operation,
+  g_signal_connect(item, "activate", G_CALLBACK(_tree_operation),
                     GINT_TO_POINTER(state));
   gtk_menu_shell_append(menu, item);
 }
@@ -757,9 +759,9 @@ static void _tree_duplicate_shape(GtkButton *button, dt_lib_module_t *self)
   g_list_free_full(items, (GDestroyNotify)gtk_tree_path_free);
 }
 
-static void _tree_cell_edited(GtkCellRendererText *cell,
-                              gchar *path_string,
-                              gchar *new_text,
+static void _tree_cell_edited(GtkCellRenderer *cell,
+                              const gchar *path_string,
+                              const gchar *new_text,
                               dt_lib_module_t *self)
 {
   dt_lib_masks_t *lm = self->data;
@@ -776,7 +778,7 @@ static void _tree_cell_edited(GtkCellRendererText *cell,
   // string. else this would convert in the xmp file into "<rdf:li/>"
   // which produces problems. we use a single whitespace as the pure
   // minimum text.
-  gchar *text = strlen(new_text) == 0 ? " " : new_text;
+  const gchar *text = strlen(new_text) == 0 ? " " : new_text;
 
   // first, we need to update the mask name
 
@@ -982,27 +984,27 @@ static int _tree_button_pressed(GtkWidget *treeview,
     if(nb == 0 || (grp && grp->type & DT_MASKS_GROUP))
     {
       item = gtk_menu_item_new_with_label(_("add brush"));
-      g_signal_connect(item, "activate", (GCallback)_tree_add_shape,
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_add_shape),
                        GINT_TO_POINTER(DT_MASKS_BRUSH));
       gtk_menu_shell_append(menu, item);
 
       item = gtk_menu_item_new_with_label(_("add circle"));
-      g_signal_connect(item, "activate", (GCallback)_tree_add_shape,
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_add_shape),
                        GINT_TO_POINTER(DT_MASKS_CIRCLE));
       gtk_menu_shell_append(menu, item);
 
       item = gtk_menu_item_new_with_label(_("add ellipse"));
-      g_signal_connect(item, "activate", (GCallback)_tree_add_shape,
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_add_shape),
                        GINT_TO_POINTER(DT_MASKS_ELLIPSE));
       gtk_menu_shell_append(menu, item);
 
       item = gtk_menu_item_new_with_label(_("add path"));
-      g_signal_connect(item, "activate", (GCallback)_tree_add_shape,
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_add_shape),
                        GINT_TO_POINTER(DT_MASKS_PATH));
       gtk_menu_shell_append(menu, item);
 
       item = gtk_menu_item_new_with_label(_("add gradient"));
-      g_signal_connect(item, "activate", (GCallback)_tree_add_shape,
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_add_shape),
                        GINT_TO_POINTER(DT_MASKS_GRADIENT));
       gtk_menu_shell_append(menu, item);
     }
@@ -1063,7 +1065,7 @@ static int _tree_button_pressed(GtkWidget *treeview,
           item = gtk_menu_item_new_with_label(str);
           g_object_set_data(G_OBJECT(item), "formid", GUINT_TO_POINTER(form->formid));
           g_object_set_data(G_OBJECT(item), "module", module);
-          g_signal_connect(G_OBJECT(item), "activate", G_CALLBACK(_tree_add_exist), grp);
+          g_signal_connect(item, "activate", G_CALLBACK(_tree_add_exist), grp);
           gtk_menu_shell_append(GTK_MENU_SHELL(menu0), item);
           has_unused_shapes = TRUE;
         }
@@ -1085,24 +1087,24 @@ static int _tree_button_pressed(GtkWidget *treeview,
         if(nb == 1)
         {
           item = gtk_menu_item_new_with_label(_("duplicate this shape"));
-          g_signal_connect(item, "activate", (GCallback)_tree_duplicate_shape, self);
+          g_signal_connect(item, "activate", G_CALLBACK(_tree_duplicate_shape), self);
           gtk_menu_shell_append(menu, item);
         }
         item = gtk_menu_item_new_with_label(_("delete this shape"));
-        g_signal_connect(item, "activate", (GCallback)_tree_delete_shape, self);
+        g_signal_connect(item, "activate", G_CALLBACK(_tree_delete_shape), self);
         gtk_menu_shell_append(menu, item);
       }
       else
       {
         item = gtk_menu_item_new_with_label(_("delete group"));
-        g_signal_connect(item, "activate", (GCallback)_tree_delete_shape, self);
+        g_signal_connect(item, "activate", G_CALLBACK(_tree_delete_shape), self);
         gtk_menu_shell_append(menu, item);
       }
     }
     else if(nb > 0 && depth < 3)
     {
       item = gtk_menu_item_new_with_label(_("remove from group"));
-      g_signal_connect(item, "activate", (GCallback)_tree_delete_shape, self);
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_delete_shape), self);
       gtk_menu_shell_append(menu, item);
     }
 
@@ -1110,7 +1112,7 @@ static int _tree_button_pressed(GtkWidget *treeview,
     {
       gtk_menu_shell_append(menu, gtk_separator_menu_item_new());
       item = gtk_menu_item_new_with_label(_("group the forms"));
-      g_signal_connect(item, "activate", (GCallback)_tree_group, self);
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_group), self);
       gtk_menu_shell_append(menu, item);
     }
 
@@ -1135,18 +1137,18 @@ static int _tree_button_pressed(GtkWidget *treeview,
       gtk_menu_shell_append(menu, gtk_separator_menu_item_new());
       item = gtk_menu_item_new_with_label(_("move up"));
       gtk_widget_set_sensitive(item, !is_first_row);
-      g_signal_connect(item, "activate", (GCallback)_tree_moveup, self);
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_moveup), self);
       gtk_menu_shell_append(menu, item);
 
       item = gtk_menu_item_new_with_label(_("move down"));
       gtk_widget_set_sensitive(item, !is_last_row);
-      g_signal_connect(item, "activate", (GCallback)_tree_movedown, self);
+      g_signal_connect(item, "activate", G_CALLBACK(_tree_movedown), self);
       gtk_menu_shell_append(menu, item);
     }
 
     gtk_menu_shell_append(menu, gtk_separator_menu_item_new());
     item = gtk_menu_item_new_with_label(_("delete unused shapes"));
-    g_signal_connect(item, "activate", (GCallback)_tree_cleanup, self);
+    g_signal_connect(item, "activate", G_CALLBACK(_tree_cleanup), self);
     gtk_menu_shell_append(menu, item);
 
     gtk_widget_show_all(GTK_WIDGET(menu));
@@ -1794,7 +1796,7 @@ void gui_init(dt_lib_module_t *self)
   d->bt_gradient = dtgtk_togglebutton_new(dtgtk_cairo_paint_masks_gradient, 0, NULL);
   dt_action_define(DT_ACTION(self), N_("shapes"), N_("add gradient"),
                    d->bt_gradient, &dt_action_def_toggle);
-  g_signal_connect(G_OBJECT(d->bt_gradient), "button-press-event",
+  g_signal_connect(d->bt_gradient, "button-press-event",
                    G_CALLBACK(_bt_add_shape), GINT_TO_POINTER(DT_MASKS_GRADIENT));
   gtk_widget_set_tooltip_text(d->bt_gradient, _("add gradient"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(d->bt_gradient), FALSE);
@@ -1802,7 +1804,7 @@ void gui_init(dt_lib_module_t *self)
   d->bt_path = dtgtk_togglebutton_new(dtgtk_cairo_paint_masks_path, 0, NULL);
   dt_action_define(DT_ACTION(self), N_("shapes"), N_("add path"),
                    d->bt_path, &dt_action_def_toggle);
-  g_signal_connect(G_OBJECT(d->bt_path), "button-press-event",
+  g_signal_connect(d->bt_path, "button-press-event",
                    G_CALLBACK(_bt_add_shape), GINT_TO_POINTER(DT_MASKS_PATH));
   gtk_widget_set_tooltip_text(d->bt_path, _("add path"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(d->bt_path), FALSE);
@@ -1810,7 +1812,7 @@ void gui_init(dt_lib_module_t *self)
   d->bt_ellipse = dtgtk_togglebutton_new(dtgtk_cairo_paint_masks_ellipse, 0, NULL);
   dt_action_define(DT_ACTION(self), N_("shapes"), N_("add ellipse"),
                    d->bt_ellipse, &dt_action_def_toggle);
-  g_signal_connect(G_OBJECT(d->bt_ellipse), "button-press-event",
+  g_signal_connect(d->bt_ellipse, "button-press-event",
                    G_CALLBACK(_bt_add_shape), GINT_TO_POINTER(DT_MASKS_ELLIPSE));
   gtk_widget_set_tooltip_text(d->bt_ellipse, _("add ellipse"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(d->bt_ellipse), FALSE);
@@ -1818,7 +1820,7 @@ void gui_init(dt_lib_module_t *self)
   d->bt_circle = dtgtk_togglebutton_new(dtgtk_cairo_paint_masks_circle, 0, NULL);
   dt_action_define(DT_ACTION(self), N_("shapes"), N_("add circle"),
                    d->bt_circle, &dt_action_def_toggle);
-  g_signal_connect(G_OBJECT(d->bt_circle), "button-press-event",
+  g_signal_connect(d->bt_circle, "button-press-event",
                    G_CALLBACK(_bt_add_shape), GINT_TO_POINTER(DT_MASKS_CIRCLE));
   gtk_widget_set_tooltip_text(d->bt_circle, _("add circle"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(d->bt_circle), FALSE);
@@ -1826,7 +1828,7 @@ void gui_init(dt_lib_module_t *self)
   d->bt_brush = dtgtk_togglebutton_new(dtgtk_cairo_paint_masks_brush, 0, NULL);
   dt_action_define(DT_ACTION(self), N_("shapes"), N_("add brush"),
                    d->bt_brush, &dt_action_def_toggle);
-  g_signal_connect(G_OBJECT(d->bt_brush), "button-press-event",
+  g_signal_connect(d->bt_brush, "button-press-event",
                    G_CALLBACK(_bt_add_shape), GINT_TO_POINTER(DT_MASKS_BRUSH));
   gtk_widget_set_tooltip_text(d->bt_brush, _("add brush"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(d->bt_brush), FALSE);
@@ -1850,7 +1852,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_tree_view_column_pack_start(col, renderer, TRUE);
   gtk_tree_view_column_add_attribute(col, renderer, "text", TREE_TEXT);
   gtk_tree_view_column_add_attribute(col, renderer, "editable", TREE_EDITABLE);
-  g_signal_connect(renderer, "edited", (GCallback)_tree_cell_edited, self);
+  g_signal_connect(renderer, "edited", G_CALLBACK(_tree_cell_edited), self);
   dt_gui_commit_on_focus_loss(renderer, NULL);
   renderer = gtk_cell_renderer_pixbuf_new();
   gtk_tree_view_column_pack_end(col, renderer, FALSE);
@@ -1865,7 +1867,7 @@ void gui_init(dt_lib_module_t *self)
   g_signal_connect(d->treeview, "query-tooltip", G_CALLBACK(_tree_query_tooltip), NULL);
   g_signal_connect(selection, "changed", G_CALLBACK(_tree_selection_change), d);
   g_signal_connect(d->treeview, "button-press-event",
-                   (GCallback)_tree_button_pressed, self);
+                   G_CALLBACK(_tree_button_pressed), self);
 
   self->widget = dt_gui_vbox
     (dt_gui_hbox
@@ -1900,7 +1902,7 @@ void gui_init(dt_lib_module_t *self)
 
     d->last_value[i] = dt_bauhaus_slider_get(slider);
     dt_gui_box_add(d->cs.container, slider);
-    g_signal_connect(G_OBJECT(slider), "value-changed",
+    g_signal_connect(slider, "value-changed",
                      G_CALLBACK(_property_changed), GINT_TO_POINTER(i));
   }
 
diff --git a/src/libs/metadata.c b/src/libs/metadata.c
index 066e5bb140bd..bffedd2da5fb 100644
--- a/src/libs/metadata.c
+++ b/src/libs/metadata.c
@@ -560,7 +560,7 @@ static void _populate_popup_multi(GtkTextView *textview,
   for(GList *item = texts; item; item = item->next)
   {
     GtkWidget *new_line = gtk_menu_item_new_with_label(item->data);
-    g_signal_connect(G_OBJECT(new_line), "activate", G_CALLBACK(_menu_line_activated), textview);
+    g_signal_connect(new_line, "activate", G_CALLBACK(_menu_line_activated), textview);
     gtk_menu_shell_append(GTK_MENU_SHELL(popup), new_line);
   }
   gtk_widget_show_all(popup);
@@ -890,7 +890,7 @@ static void _menuitem_preferences(GtkMenuItem *menuitem,
     (_("display name"), renderer,
      "text", DT_METADATA_PREF_COL_NAME, NULL);
   g_object_set(renderer, "editable", TRUE, NULL);
-  g_signal_connect(G_OBJECT(renderer), "edited", G_CALLBACK(_display_name_edited_callback), store);
+  g_signal_connect(renderer, "edited", G_CALLBACK(_display_name_edited_callback), store);
   dt_gui_commit_on_focus_loss(renderer, &active_editable);
   gtk_tree_view_column_set_expand(column, TRUE);
   gtk_tree_view_append_column(GTK_TREE_VIEW(view), column);
@@ -908,7 +908,7 @@ static void _menuitem_preferences(GtkMenuItem *menuitem,
 
   // drag & drop
   gtk_tree_view_set_reorderable(GTK_TREE_VIEW(view), TRUE);
-  g_signal_connect(G_OBJECT(model), "row-inserted", G_CALLBACK(_drag_data_inserted), d);
+  g_signal_connect(model, "row-inserted", G_CALLBACK(_drag_data_inserted), d);
 
   GtkWidget *header = gtk_tree_view_column_get_button(column);
   gtk_widget_set_tooltip_text(header,
@@ -932,11 +932,11 @@ static void _menuitem_preferences(GtkMenuItem *menuitem,
 
   GtkWidget *plus = dtgtk_button_new(dtgtk_cairo_paint_plus_simple, 0, NULL);
   gtk_widget_set_tooltip_text(plus, _("add metadata tags"));
-  g_signal_connect(G_OBJECT(plus), "clicked", G_CALLBACK(_add_tag_button_clicked), (gpointer)d);
+  g_signal_connect(plus, "clicked", G_CALLBACK(_add_tag_button_clicked), (gpointer)d);
 
   GtkWidget *minus = dtgtk_button_new(dtgtk_cairo_paint_minus_simple, 0, NULL);
   gtk_widget_set_tooltip_text(minus, _("delete metadata tag"));
-  g_signal_connect(G_OBJECT(minus), "clicked", G_CALLBACK(_delete_tag_button_clicked), (gpointer)d);
+  g_signal_connect(minus, "clicked", G_CALLBACK(_delete_tag_button_clicked), (gpointer)d);
   d->delete_button = minus;
 
 #ifdef GDK_WINDOWING_QUARTZ
@@ -1119,7 +1119,7 @@ static void _menuitem_preferences(GtkMenuItem *menuitem,
 void set_preferences(void *menu, dt_lib_module_t *self)
 {
   GtkWidget *mi = gtk_menu_item_new_with_label(_("preferences..."));
-  g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(_menuitem_preferences), self);
+  g_signal_connect(mi, "activate", G_CALLBACK(_menuitem_preferences), self);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
 
diff --git a/src/libs/metadata_view.c b/src/libs/metadata_view.c
index f4e1abd11b09..b162629912a7 100644
--- a/src/libs/metadata_view.c
+++ b/src/libs/metadata_view.c
@@ -1203,7 +1203,7 @@ static void _lib_metadata_refill_grid(dt_lib_module_t *self)
       // film roll jump to:
       if(d->filmroll_event && GTK_IS_WIDGET(d->filmroll_event))
         g_signal_handlers_disconnect_by_func(d->filmroll_event, G_CALLBACK(_filmroll_clicked), NULL);
-      g_signal_connect(G_OBJECT(w_value), "button-press-event", G_CALLBACK(_filmroll_clicked), NULL);
+      g_signal_connect(w_value, "button-press-event", G_CALLBACK(_filmroll_clicked), NULL);
       d->filmroll_event = G_OBJECT(w_value);
     }
 
@@ -1476,7 +1476,7 @@ void _menuitem_preferences(GtkMenuItem *menuitem, dt_lib_module_t *self)
 
   // drag & drop
   gtk_tree_view_set_reorderable(GTK_TREE_VIEW(view), TRUE);
-  g_signal_connect(G_OBJECT(model), "row-inserted", G_CALLBACK(_drag_data_inserted), NULL);
+  g_signal_connect(model, "row-inserted", G_CALLBACK(_drag_data_inserted), NULL);
   GtkWidget *w = dt_gui_scroll_wrap(view);
   gtk_widget_set_size_request(w, -1, DT_PIXEL_APPLY_DPI(600));
   gtk_scrolled_window_set_policy(GTK_SCROLLED_WINDOW(w), GTK_POLICY_NEVER, GTK_POLICY_ALWAYS);
@@ -1541,7 +1541,7 @@ void _menuitem_preferences(GtkMenuItem *menuitem, dt_lib_module_t *self)
 void set_preferences(void *menu, dt_lib_module_t *self)
 {
   GtkWidget *mi = gtk_menu_item_new_with_label(_("preferences..."));
-  g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(_menuitem_preferences), self);
+  g_signal_connect(mi, "activate", G_CALLBACK(_menuitem_preferences), self);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
 
diff --git a/src/libs/modulegroups.c b/src/libs/modulegroups.c
index 7690e939dbfc..79ded6ffd39d 100644
--- a/src/libs/modulegroups.c
+++ b/src/libs/modulegroups.c
@@ -468,7 +468,7 @@ static void _basics_add_widget(dt_lib_module_t *self, dt_lib_modulegroups_basic_
       gtk_label_set_xalign(GTK_LABEL(lb), 0.0);
       gtk_widget_set_name(lb, "basics-iop_name");
       gtk_container_add(GTK_CONTAINER(evb), lb);
-      g_signal_connect(G_OBJECT(evb), "button-press-event", G_CALLBACK(_basics_on_off_label_callback), btn);
+      g_signal_connect(evb, "button-press-event", G_CALLBACK(_basics_on_off_label_callback), btn);
       gtk_box_pack_start(GTK_BOX(item->box), evb, FALSE, TRUE, 0);
 
       // disable widget if needed (multiinstance)
@@ -576,7 +576,7 @@ static void _basics_add_widget(dt_lib_module_t *self, dt_lib_modulegroups_basic_
     g_signal_connect(item->widget      , "notify::visible", G_CALLBACK(_sync_visibility), item);
     g_signal_connect(item->old_parent  , "notify::visible", G_CALLBACK(_sync_visibility), item);
     g_signal_connect(item->temp_widget , "notify::visible", G_CALLBACK(_sync_visibility), item);
-    g_signal_connect(G_OBJECT(item->temp_widget), "destroy", G_CALLBACK(gtk_widget_destroyed), &item->temp_widget);
+    g_signal_connect(item->temp_widget, "destroy", G_CALLBACK(gtk_widget_destroyed), &item->temp_widget);
     g_signal_connect_swapped(G_OBJECT(item->temp_widget), "destroy", G_CALLBACK(_basics_remove_widget), item);
 
     _sync_visibility(item->widget, NULL, item);
@@ -612,7 +612,7 @@ static void _basics_add_widget(dt_lib_module_t *self, dt_lib_modulegroups_basic_
     gtk_widget_set_name(wbt, "basics-link");
     gtk_widget_set_valign(wbt, GTK_ALIGN_CENTER);
     g_free(tt);
-    g_signal_connect(G_OBJECT(wbt), "button-press-event", G_CALLBACK(_basics_goto_module), item->module);
+    g_signal_connect(wbt, "button-press-event", G_CALLBACK(_basics_goto_module), item->module);
     gtk_box_pack_end(GTK_BOX(compact_ui ? hbox_basic : header_box), wbt, FALSE, FALSE, 0);
 
     // we create a button to open the presets menu
@@ -2006,7 +2006,7 @@ static void _manage_editor_basics_update_list(dt_lib_module_t *self)
 
             gtk_widget_set_tooltip_text(btn, _("remove this widget"));
             g_object_set_data(G_OBJECT(btn), "widget_id", item->id);
-            g_signal_connect(G_OBJECT(btn), "button-press-event",
+            g_signal_connect(btn, "button-press-event",
                              G_CALLBACK(_manage_editor_basics_remove), self);
             gtk_box_pack_end(GTK_BOX(hb), btn, FALSE, TRUE, 0);
           }
@@ -2130,7 +2130,7 @@ static void _manage_editor_module_update_list(dt_lib_module_t *self,
           gtk_widget_set_tooltip_text(btn, _("remove this module"));
           g_object_set_data(G_OBJECT(btn), "module_name", module->op);
           g_object_set_data(G_OBJECT(btn), "group", gr);
-          g_signal_connect(G_OBJECT(btn), "button-press-event",
+          g_signal_connect(btn, "button-press-event",
                            G_CALLBACK(_manage_editor_module_remove), self);
           gtk_box_pack_end(GTK_BOX(hb), btn, FALSE, TRUE, 0);
         }
@@ -2376,7 +2376,7 @@ static void _manage_module_add_popup(GtkWidget *widget,
           gtk_widget_set_tooltip_text(GTK_WIDGET(smir), _("add this module"));
           g_object_set_data(G_OBJECT(smir), "module_op", module->op);
           g_object_set_data(G_OBJECT(smir), "group", gr);
-          g_signal_connect(G_OBJECT(smir), "activate", callback, data);
+          g_signal_connect(smir, "activate", G_CALLBACK(callback), data);
           gtk_menu_shell_insert(GTK_MENU_SHELL(pop), GTK_WIDGET(smir), nba);
         }
         GtkMenuItem *smi = (GtkMenuItem *)gtk_menu_item_new_with_label(module->name());
@@ -2384,7 +2384,7 @@ static void _manage_module_add_popup(GtkWidget *widget,
         gtk_widget_set_tooltip_text(GTK_WIDGET(smi), _("add this module"));
         g_object_set_data(G_OBJECT(smi), "module_op", module->op);
         g_object_set_data(G_OBJECT(smi), "group", gr);
-        g_signal_connect(G_OBJECT(smi), "activate", callback, data);
+        g_signal_connect(smi, "activate", G_CALLBACK(callback), data);
         gtk_menu_shell_prepend(GTK_MENU_SHELL(sm_all), GTK_WIDGET(smi));
       }
       else if(toggle)
@@ -2394,7 +2394,7 @@ static void _manage_module_add_popup(GtkWidget *widget,
         gtk_widget_set_tooltip_text(GTK_WIDGET(smi), _("remove this module"));
         g_object_set_data(G_OBJECT(smi), "module_op", module->op);
         g_object_set_data(G_OBJECT(smi), "group", gr);
-        g_signal_connect(G_OBJECT(smi), "activate", callback, data);
+        g_signal_connect(smi, "activate", G_CALLBACK(callback), data);
         gtk_menu_shell_insert(GTK_MENU_SHELL(pop), GTK_WIDGET(smi), 0);
         nba++;
       }
@@ -2548,7 +2548,7 @@ static GtkWidget *_build_menu_from_actions(dt_action_t *actions,
             gtk_widget_set_tooltip_text(item_top, _("remove this widget"));
             gtk_widget_set_name(item_top, "modulegroups-popup-item");
             g_object_set_data(G_OBJECT(item_top), "widget_id", action);
-            g_signal_connect(G_OBJECT(item_top), "activate", callback, self);
+            g_signal_connect(item_top, "activate", G_CALLBACK(callback), self);
             gtk_menu_shell_insert(GTK_MENU_SHELL(base_menu), item_top, *num_selected);
             ++*num_selected;
           }
@@ -2565,7 +2565,7 @@ static GtkWidget *_build_menu_from_actions(dt_action_t *actions,
             gtk_widget_set_tooltip_text(item_top, _("add this widget"));
             gtk_widget_set_name(item_top, "modulegroups-popup-item");
             g_object_set_data(G_OBJECT(item_top), "widget_id", action);
-            g_signal_connect(G_OBJECT(item_top), "activate", callback, self);
+            g_signal_connect(item_top, "activate", G_CALLBACK(callback), self);
             gtk_menu_shell_append(GTK_MENU_SHELL(base_menu), item_top);
           }
           g_free(delimited_id);
@@ -2583,7 +2583,7 @@ static GtkWidget *_build_menu_from_actions(dt_action_t *actions,
         }
 
         g_object_set_data(G_OBJECT(item), "widget_id", action);
-        g_signal_connect(G_OBJECT(item), "activate", callback, self);
+        g_signal_connect(item, "activate", G_CALLBACK(callback), self);
         g_free(action_id);
       }
       g_free(action_label);
@@ -2743,7 +2743,7 @@ static gboolean _manage_direct_active_popup(GtkWidget *widget,
           " regardless of whether or not they are currently enabled"));
     gtk_widget_set_name(smt, "modulegroups-popup-item");
     gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(smt), d->full_active);
-    g_signal_connect(G_OBJECT(smt), "toggled",
+    g_signal_connect(smt, "toggled",
                      G_CALLBACK(_manage_direct_full_active_toggled), self);
     gtk_menu_shell_append(GTK_MENU_SHELL(pop), smt);
 
@@ -2919,10 +2919,10 @@ void gui_init(dt_lib_module_t *self)
   dt_action_define(&darktable.view_manager->proxy.darkroom.view->actions, NULL, N_("search modules"), d->text_entry, &dt_action_def_entry);
   gtk_entry_set_placeholder_text(GTK_ENTRY(d->text_entry),
                                  _("search modules by name or tag"));
-  g_signal_connect(G_OBJECT(d->text_entry), "search-changed",
+  g_signal_connect(d->text_entry, "search-changed",
                    G_CALLBACK(_text_entry_changed_callback), self);
-  g_signal_connect(G_OBJECT(d->text_entry), "stop-search",
-                   G_CALLBACK(dt_gui_search_stop), dt_ui_center(darktable.gui->ui));
+  g_signal_connect(GTK_SEARCH_ENTRY(d->text_entry), "stop-search",
+                   G_CALLBACK(dt_gui_search_stop), (GtkTreeView*)dt_ui_center(darktable.gui->ui));
   g_signal_connect_data(G_OBJECT(d->text_entry), "focus-in-event",
                         G_CALLBACK(gtk_widget_show),
                         d->hbox_search_box, NULL, G_CONNECT_AFTER | G_CONNECT_SWAPPED);
@@ -3199,7 +3199,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("basic icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "basic");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3210,7 +3210,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("active icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "active");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3221,7 +3221,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("color icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "color");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3232,7 +3232,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("correct icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "correct");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3243,7 +3243,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("effect icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "effect");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3254,7 +3254,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("favorites icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "favorites");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3265,7 +3265,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("tone icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "tone");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3276,7 +3276,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("grading icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "grading");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3287,7 +3287,7 @@ static void _manage_editor_group_icon_popup(GtkWidget *btn,
   gtk_box_pack_start(GTK_BOX(hb), ic, FALSE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("technical icon")), TRUE, TRUE, 0);
   g_object_set_data(G_OBJECT(eb), "ic_name", "technical");
-  g_signal_connect(G_OBJECT(eb), "button-press-event",
+  g_signal_connect(eb, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_changed), gr);
   gtk_container_add(GTK_CONTAINER(eb), hb);
   gtk_box_pack_start(GTK_BOX(vb), eb, FALSE, TRUE, 0);
@@ -3345,7 +3345,7 @@ static GtkWidget *_manage_editor_group_init_basics_box(dt_lib_module_t *self)
                                      CPF_DIRECTION_LEFT, NULL);
     gtk_widget_set_tooltip_text(bt, _("add widget to the quick access panel"));
     gtk_widget_set_name(bt, "modulegroups-btn");
-    g_signal_connect(G_OBJECT(bt), "button-press-event",
+    g_signal_connect(bt, "button-press-event",
                      G_CALLBACK(_manage_editor_basics_add_popup), self);
     gtk_widget_set_halign(hb4, GTK_ALIGN_CENTER);
     gtk_box_pack_start(GTK_BOX(hb4), bt, FALSE, FALSE, 0);
@@ -3378,7 +3378,7 @@ static GtkWidget *_manage_editor_group_init_modules_box(dt_lib_module_t *self,
   gtk_widget_set_name(btn, "modulegroups-group-icon");
   gtk_widget_set_tooltip_text(btn, _("group icon"));
   gtk_widget_set_sensitive(btn, !d->edit_ro);
-  g_signal_connect(G_OBJECT(btn), "button-press-event",
+  g_signal_connect(btn, "button-press-event",
                    G_CALLBACK(_manage_editor_group_icon_popup), self);
   g_object_set_data(G_OBJECT(btn), "group", gr);
   gtk_box_pack_start(GTK_BOX(hb3), btn, FALSE, TRUE, 0);
@@ -3389,7 +3389,7 @@ static GtkWidget *_manage_editor_group_init_modules_box(dt_lib_module_t *self,
   gtk_widget_set_tooltip_text(tb, _("group name"));
   g_object_set_data(G_OBJECT(tb), "group", gr);
   gtk_widget_set_sensitive(tb, !d->edit_ro);
-  g_signal_connect(G_OBJECT(tb), "changed",
+  g_signal_connect(tb, "changed",
                    G_CALLBACK(_manage_editor_group_name_changed), self);
   gtk_entry_set_text(GTK_ENTRY(tb), gr->name);
   gtk_box_pack_start(GTK_BOX(hb3), tb, TRUE, TRUE, 0);
@@ -3400,7 +3400,7 @@ static GtkWidget *_manage_editor_group_init_modules_box(dt_lib_module_t *self,
     btn = dtgtk_button_new(dtgtk_cairo_paint_remove, 0, NULL);
     gtk_widget_set_tooltip_text(btn, _("remove group"));
     g_object_set_data(G_OBJECT(btn), "group", gr);
-    g_signal_connect(G_OBJECT(btn), "button-press-event",
+    g_signal_connect(btn, "button-press-event",
                      G_CALLBACK(_manage_editor_group_remove), self);
     gtk_box_pack_end(GTK_BOX(hb3), btn, FALSE, TRUE, 0);
   }
@@ -3428,7 +3428,7 @@ static GtkWidget *_manage_editor_group_init_modules_box(dt_lib_module_t *self,
     gtk_widget_set_name(btn, "modulegroups-btn");
     gtk_widget_set_tooltip_text(btn, _("move group to the left"));
     g_object_set_data(G_OBJECT(btn), "group", gr);
-    g_signal_connect(G_OBJECT(btn), "button-press-event",
+    g_signal_connect(btn, "button-press-event",
                      G_CALLBACK(_manage_editor_group_move_left), self);
     gtk_box_pack_start(GTK_BOX(hb4), btn, FALSE, FALSE, 2);
 
@@ -3439,7 +3439,7 @@ static GtkWidget *_manage_editor_group_init_modules_box(dt_lib_module_t *self,
     gtk_widget_set_tooltip_text(bt, _("add module to the group"));
     gtk_widget_set_name(bt, "modulegroups-btn");
     g_object_set_data(G_OBJECT(bt), "group", gr);
-    g_signal_connect(G_OBJECT(bt), "button-press-event",
+    g_signal_connect(bt, "button-press-event",
                      G_CALLBACK(_manage_editor_module_add_popup), self);
     gtk_widget_set_halign(plusbox, GTK_ALIGN_CENTER);
     gtk_box_pack_start(GTK_BOX(plusbox), bt, FALSE, FALSE, 0);
@@ -3450,7 +3450,7 @@ static GtkWidget *_manage_editor_group_init_modules_box(dt_lib_module_t *self,
     gtk_widget_set_name(btn, "modulegroups-btn");
     gtk_widget_set_tooltip_text(btn, _("move group to the right"));
     g_object_set_data(G_OBJECT(btn), "group", gr);
-    g_signal_connect(G_OBJECT(btn), "button-press-event",
+    g_signal_connect(btn, "button-press-event",
                      G_CALLBACK(_manage_editor_group_move_right), self);
     gtk_box_pack_end(GTK_BOX(hb4), btn, FALSE, FALSE, 2);
 
@@ -3653,7 +3653,7 @@ static void _manage_editor_preset_action(GtkWidget *btn,
                             10 + g_utf8_strlen(gtk_window_get_title(GTK_WINDOW(dialog)),
                                                -1));
   gpointer verify_params[] = {dialog, names, lb};
-  g_signal_connect(G_OBJECT(tb), "changed",
+  g_signal_connect(tb, "changed",
                    G_CALLBACK(_manage_editor_preset_name_verify), verify_params);
   dt_gui_dialog_add(GTK_DIALOG(dialog), gtk_label_new(_("new preset name:")), tb, lb);
   gtk_widget_show_all(dialog);
@@ -3985,7 +3985,7 @@ static void _manage_show_window(dt_lib_module_t *self)
   GtkWidget *hb2 = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
   gtk_box_pack_start(GTK_BOX(hb2), gtk_label_new(_("preset: ")), FALSE, TRUE, 2);
   d->presets_combo = gtk_combo_box_text_new();
-  g_signal_connect(G_OBJECT(d->presets_combo), "changed",
+  g_signal_connect(d->presets_combo, "changed",
                    G_CALLBACK(_manage_preset_change), self);
   gtk_box_pack_start(GTK_BOX(hb2), d->presets_combo, TRUE, TRUE, 2);
   gtk_box_pack_start(GTK_BOX(vb), hb2, FALSE, TRUE, 2);
@@ -4014,11 +4014,11 @@ static void _manage_show_window(dt_lib_module_t *self)
   vb = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
   gtk_widget_set_name(vb, "modulegroups-top-boxes");
   d->edit_search_cb = gtk_check_button_new_with_label(_("show search line"));
-  g_signal_connect(G_OBJECT(d->edit_search_cb), "toggled",
+  g_signal_connect(d->edit_search_cb, "toggled",
                    G_CALLBACK(_manage_editor_search_toggle), self);
   gtk_box_pack_start(GTK_BOX(vb), d->edit_search_cb, FALSE, TRUE, 0);
   d->basics_chkbox = gtk_check_button_new_with_label(_("show quick access panel"));
-  g_signal_connect(G_OBJECT(d->basics_chkbox), "toggled",
+  g_signal_connect(d->basics_chkbox, "toggled",
                    G_CALLBACK(_manage_editor_basics_toggle), self);
   gtk_box_pack_start(GTK_BOX(vb), d->basics_chkbox, FALSE, TRUE, 0);
   d->edit_full_active_cb =
@@ -4027,7 +4027,7 @@ static void _manage_show_window(dt_lib_module_t *self)
       d->edit_full_active_cb,
       _("show modules that are present in the history stack,"
         " regardless of whether or not they are currently enabled"));
-  g_signal_connect(G_OBJECT(d->edit_full_active_cb), "toggled",
+  g_signal_connect(d->edit_full_active_cb, "toggled",
                    G_CALLBACK(_manage_editor_full_active_toggle),
                    self);
   gtk_box_pack_start(GTK_BOX(vb), d->edit_full_active_cb, FALSE, TRUE, 0);
@@ -4040,7 +4040,7 @@ static void _manage_show_window(dt_lib_module_t *self)
   gtk_widget_set_sensitive(d->edit_autoapply_chkbox, FALSE); // always readonly. change are done with the button...
   gtk_box_pack_start(GTK_BOX(hb2), d->edit_autoapply_chkbox, FALSE, TRUE, 0);
   d->edit_autoapply_btn = dtgtk_button_new(dtgtk_cairo_paint_preferences, 0, NULL);
-  g_signal_connect(G_OBJECT(d->edit_autoapply_btn), "clicked",
+  g_signal_connect(d->edit_autoapply_btn, "clicked",
                    G_CALLBACK(_preset_autoapply_edit), self);
   gtk_widget_set_name(d->edit_autoapply_btn, "modulegroups-autoapply-btn");
   gtk_box_pack_start(GTK_BOX(hb2), d->edit_autoapply_btn, FALSE, FALSE, 2);
@@ -4055,7 +4055,7 @@ static void _manage_show_window(dt_lib_module_t *self)
   gtk_box_pack_start(GTK_BOX(hb), gtk_label_new(_("module groups")), FALSE, TRUE, 0);
   d->preset_btn_add_group = dtgtk_button_new(dtgtk_cairo_paint_square_plus,
                                              CPF_DIRECTION_LEFT, NULL);
-  g_signal_connect(G_OBJECT(d->preset_btn_add_group), "button-press-event",
+  g_signal_connect(d->preset_btn_add_group, "button-press-event",
                    G_CALLBACK(_manage_editor_group_add),
                    self);
   gtk_box_pack_start(GTK_BOX(hb), d->preset_btn_add_group, FALSE, FALSE, 0);
@@ -4080,7 +4080,7 @@ static void _manage_show_window(dt_lib_module_t *self)
   hb2 = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
 
   d->preset_reset_btn = gtk_button_new_with_label(_("reset"));
-  g_signal_connect(G_OBJECT(d->preset_reset_btn), "button-press-event",
+  g_signal_connect(d->preset_reset_btn, "button-press-event",
                    G_CALLBACK(_manage_editor_reset), self);
   gtk_box_pack_end(GTK_BOX(hb2), d->preset_reset_btn, FALSE, TRUE, 0);
 
diff --git a/src/libs/navigation.c b/src/libs/navigation.c
index 697a3af217cf..f0a542f12552 100644
--- a/src/libs/navigation.c
+++ b/src/libs/navigation.c
@@ -214,17 +214,17 @@ void gui_init(dt_lib_module_t *self)
 
   /* connect callbacks */
   gtk_widget_set_app_paintable(thumbnail, TRUE);
-  g_signal_connect(G_OBJECT(thumbnail), "draw",
+  g_signal_connect(thumbnail, "draw",
                    G_CALLBACK(_lib_navigation_draw_callback), self);
-  g_signal_connect(G_OBJECT(thumbnail), "button-press-event",
+  g_signal_connect(thumbnail, "button-press-event",
                    G_CALLBACK(_lib_navigation_button_press_callback), self);
-  g_signal_connect(G_OBJECT(thumbnail), "scroll-event",
+  g_signal_connect(thumbnail, "scroll-event",
                    G_CALLBACK(_lib_navigation_button_press_callback), self);
-  g_signal_connect(G_OBJECT(thumbnail), "button-release-event",
+  g_signal_connect(thumbnail, "button-release-event",
                    G_CALLBACK(_lib_navigation_button_release_callback), self);
-  g_signal_connect(G_OBJECT(thumbnail), "motion-notify-event",
+  g_signal_connect(thumbnail, "motion-notify-event",
                    G_CALLBACK(_lib_navigation_motion_notify_callback), self);
-  g_signal_connect(G_OBJECT(thumbnail), "leave-notify-event",
+  g_signal_connect(thumbnail, "leave-notify-event",
                    G_CALLBACK(_lib_navigation_leave_notify_callback), self);
 
   /* set size of navigation draw area */
diff --git a/src/libs/print_settings.c b/src/libs/print_settings.c
index f0f4a9820a95..9b98272746ae 100644
--- a/src/libs/print_settings.c
+++ b/src/libs/print_settings.c
@@ -1021,7 +1021,7 @@ _lock_callback(GtkWidget *button, dt_lib_module_t *self)
 }
 
 static void
-_alignment_callback(GtkWidget *tb, dt_lib_module_t *self)
+_alignment_callback(GtkDarktableToggleButton *tb, dt_lib_module_t *self)
 {
   if(darktable.gui->reset) return;
 
@@ -1033,7 +1033,7 @@ _alignment_callback(GtkWidget *tb, dt_lib_module_t *self)
     /* block signal handler */
     g_signal_handlers_block_by_func(ps->dtba[i],_alignment_callback, self);
 
-    if(GTK_WIDGET(ps->dtba[i]) == tb)
+    if(ps->dtba[i] == tb)
     {
       gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(ps->dtba[i]), TRUE);
       index=i;
@@ -2484,7 +2484,7 @@ void gui_init(dt_lib_module_t *self)
   d->printers = dt_bauhaus_combobox_new_action(DT_ACTION(self));
 
   gtk_box_pack_start(GTK_BOX(self->widget), d->printers, TRUE, TRUE, 0);
-  g_signal_connect(G_OBJECT(d->printers), "value-changed",
+  g_signal_connect(d->printers, "value-changed",
                    G_CALLBACK(_printer_changed), self);
 
   //// media
@@ -2493,7 +2493,7 @@ void gui_init(dt_lib_module_t *self)
 
   dt_bauhaus_widget_set_label(d->media, N_("printer"), N_("media"));
 
-  g_signal_connect(G_OBJECT(d->media), "value-changed",
+  g_signal_connect(d->media, "value-changed",
                    G_CALLBACK(_media_changed), self);
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(d->media), TRUE, TRUE, 0);
 
@@ -2549,8 +2549,8 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_markup(d->pprofile, tooltip);
   g_free(tooltip);
 
-  g_signal_connect(G_OBJECT(d->pprofile), "value-changed",
-                   G_CALLBACK(_printer_profile_changed), (gpointer)self);
+  g_signal_connect(d->pprofile, "value-changed",
+                   G_CALLBACK(_printer_profile_changed), self);
 
   //  Add printer intent combo
 
@@ -2570,7 +2570,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_box_pack_start(GTK_BOX(self->widget),
                      GTK_WIDGET(d->black_point_compensation), TRUE, FALSE, 0);
   g_signal_connect(d->black_point_compensation, "toggled",
-                   G_CALLBACK(_printer_bpc_callback), (gpointer)self);
+                   G_CALLBACK(_printer_bpc_callback), self);
 
   d->v_black_point_compensation =
     dt_conf_get_bool(PRINT_CONFIG_PREFIX "black_point_compensation");
@@ -2594,7 +2594,7 @@ void gui_init(dt_lib_module_t *self)
 
   dt_bauhaus_widget_set_label(d->papers, NULL, N_("paper size"));
 
-  g_signal_connect(G_OBJECT(d->papers), "value-changed", G_CALLBACK(_paper_changed), self);
+  g_signal_connect(d->papers, "value-changed", G_CALLBACK(_paper_changed), self);
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(d->papers), TRUE, TRUE, 0);
 
   //// portrait / landscape
@@ -2677,15 +2677,15 @@ void gui_init(dt_lib_module_t *self)
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(d->b_left), left_b);
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(d->b_right), right_b);
 
-  g_signal_connect(G_OBJECT (d->b_top), "value-changed",
+  g_signal_connect(d->b_top, "value-changed",
                    G_CALLBACK (_top_border_callback), self);
-  g_signal_connect(G_OBJECT (d->b_bottom), "value-changed",
+  g_signal_connect(d->b_bottom, "value-changed",
                    G_CALLBACK (_bottom_border_callback), self);
-  g_signal_connect(G_OBJECT (d->b_left), "value-changed",
+  g_signal_connect(d->b_left, "value-changed",
                    G_CALLBACK (_left_border_callback), self);
-  g_signal_connect(G_OBJECT (d->b_right), "value-changed",
+  g_signal_connect(d->b_right, "value-changed",
                    G_CALLBACK (_right_border_callback), self);
-  g_signal_connect(G_OBJECT(d->lock_button), "toggled",
+  g_signal_connect(d->lock_button, "toggled",
                    G_CALLBACK(_lock_callback), self);
 
   gtk_widget_set_halign(GTK_WIDGET(hboxdim), GTK_ALIGN_CENTER);
@@ -2715,12 +2715,12 @@ void gui_init(dt_lib_module_t *self)
 
     gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(vbox), TRUE, TRUE, 0);
 
-    g_signal_connect(G_OBJECT(d->grid_size), "value-changed",
+    g_signal_connect(d->grid_size, "value-changed",
                      G_CALLBACK(_grid_size_changed), self);
-    g_signal_connect(G_OBJECT(d->grid), "toggled",
+    g_signal_connect(d->grid, "toggled",
                      G_CALLBACK(_grid_callback), self);
     g_signal_connect(d->snap_grid, "toggled",
-                     G_CALLBACK(_snap_grid_callback), (gpointer)self);
+                     G_CALLBACK(_snap_grid_callback), self);
   }
 
   d->borderless = gtk_check_button_new_with_label(_("borderless mode required"));
@@ -2752,8 +2752,8 @@ void gui_init(dt_lib_module_t *self)
         = DTGTK_TOGGLEBUTTON(dtgtk_togglebutton_new(dtgtk_cairo_paint_alignment,
                                                     (CPF_SPECIAL_FLAG << i), NULL));
     gtk_grid_attach (GTK_GRID (bat), GTK_WIDGET (d->dtba[i]), (i%3), i/3, 1, 1);
-    g_signal_connect (G_OBJECT (d->dtba[i]), "toggled",
-                      G_CALLBACK (_alignment_callback), self);
+    g_signal_connect(d->dtba[i], "toggled",
+                     G_CALLBACK (_alignment_callback), self);
   }
 
   GtkWidget *hbox22 = gtk_box_new(GTK_ORIENTATION_HORIZONTAL,0);
@@ -2838,14 +2838,14 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_add_events(d->b_width, GDK_BUTTON_PRESS_MASK);
   gtk_widget_add_events(d->b_height, GDK_BUTTON_PRESS_MASK);
 
-  g_signal_connect(G_OBJECT(d->b_x), "value-changed",
-                   G_CALLBACK(_x_changed), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->b_y), "value-changed",
-                   G_CALLBACK(_y_changed), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->b_width), "value-changed",
-                   G_CALLBACK(_width_changed), (gpointer)d);
-  g_signal_connect(G_OBJECT(d->b_height), "value-changed",
-                   G_CALLBACK(_height_changed), (gpointer)d);
+  g_signal_connect(d->b_x, "value-changed",
+                   G_CALLBACK(_x_changed), d);
+  g_signal_connect(d->b_y, "value-changed",
+                   G_CALLBACK(_y_changed), d);
+  g_signal_connect(d->b_width, "value-changed",
+                   G_CALLBACK(_width_changed), d);
+  g_signal_connect(d->b_height, "value-changed",
+                   G_CALLBACK(_height_changed), d);
 
   ////////////////////////// PRINT SETTINGS
 
@@ -2897,8 +2897,8 @@ void gui_init(dt_lib_module_t *self)
   gtk_widget_set_tooltip_markup(d->profile, tooltip);
   g_free(tooltip);
 
-  g_signal_connect(G_OBJECT(d->profile), "value-changed",
-                   G_CALLBACK(_profile_changed), (gpointer)self);
+  g_signal_connect(d->profile, "value-changed",
+                   G_CALLBACK(_profile_changed), self);
 
   //  Add export intent combo
 
@@ -2918,7 +2918,7 @@ void gui_init(dt_lib_module_t *self)
 
   GtkWidget *styles_button = dtgtk_button_new(dtgtk_cairo_paint_styles, 0, NULL);
   gtk_widget_set_halign(styles_button,GTK_ALIGN_END);
-  g_signal_connect(G_OBJECT(styles_button), "clicked", G_CALLBACK(_style_popupmenu_callback), (gpointer)d);
+  g_signal_connect(styles_button, "clicked", G_CALLBACK(_style_popupmenu_callback), d);
   gtk_widget_set_tooltip_text(styles_button, _("select style to be applied on printing"));
   GtkBox *style_box = (GtkBox*)gtk_box_new(GTK_ORIENTATION_HORIZONTAL,0);
   gtk_widget_set_tooltip_text(GTK_WIDGET(style_box), _("temporary style to use while printing"));
diff --git a/src/libs/recentcollect.c b/src/libs/recentcollect.c
index ef2d291aad63..596daaced6a0 100644
--- a/src/libs/recentcollect.c
+++ b/src/libs/recentcollect.c
@@ -278,7 +278,7 @@ void _menuitem_preferences(GtkMenuItem *menuitem, dt_lib_module_t *self)
           d->items = g_list_append(d->items, item);
           item->button = gtk_button_new();
           gtk_box_pack_start(GTK_BOX(box), item->button, FALSE, TRUE, 0);
-          g_signal_connect(G_OBJECT(item->button), "clicked", G_CALLBACK(_button_pressed), (gpointer)self);
+          g_signal_connect(item->button, "clicked", G_CALLBACK(_button_pressed), (gpointer)self);
           gtk_widget_set_no_show_all(item->button, TRUE);
           gtk_widget_set_name(GTK_WIDGET(item->button), "recent-collection-button");
           gtk_widget_set_visible(item->button, FALSE);
@@ -295,7 +295,7 @@ void _menuitem_preferences(GtkMenuItem *menuitem, dt_lib_module_t *self)
 void set_preferences(void *menu, dt_lib_module_t *self)
 {
   GtkWidget *mi = gtk_menu_item_new_with_label(_("preferences..."));
-  g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(_menuitem_preferences), self);
+  g_signal_connect(mi, "activate", G_CALLBACK(_menuitem_preferences), self);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
 
@@ -333,7 +333,7 @@ void gui_init(dt_lib_module_t *self)
     d->items = g_list_append(d->items, item);
     item->button = gtk_button_new();
     gtk_box_pack_start(GTK_BOX(box), item->button, FALSE, TRUE, 0);
-    g_signal_connect(G_OBJECT(item->button), "clicked", G_CALLBACK(_button_pressed), (gpointer)self);
+    g_signal_connect(GTK_BUTTON(item->button), "clicked", G_CALLBACK(_button_pressed), self);
     gtk_widget_set_no_show_all(item->button, TRUE);
     dt_gui_add_class(GTK_WIDGET(item->button), "dt_transparent_background");
     gtk_widget_set_name(GTK_WIDGET(item->button), "recent-collection-button");
diff --git a/src/libs/select.c b/src/libs/select.c
index 020a43a308bc..28df825150c4 100644
--- a/src/libs/select.c
+++ b/src/libs/select.c
@@ -259,7 +259,7 @@ static int lua_register_selection(lua_State *L)
   lua_callback_data * data = malloc(sizeof(lua_callback_data));
   data->key = strdup(name);
   data->self = self;
-  gulong s = g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(lua_button_clicked), data);
+  gulong s = g_signal_connect_data(button, "clicked", G_CALLBACK(lua_button_clicked), data, NULL, 0);
 
   dt_lua_module_entry_push(L, "lib", self->plugin_name);
   lua_getiuservalue(L, -1, 1);
diff --git a/src/libs/session.c b/src/libs/session.c
index c2deb8166b41..8ba5a5b65a35 100644
--- a/src/libs/session.c
+++ b/src/libs/session.c
@@ -107,7 +107,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(hbox), TRUE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(lib->gui.button1), TRUE, TRUE, 0);
 
-  g_signal_connect(G_OBJECT(lib->gui.button1), "clicked", G_CALLBACK(create_callback), self);
+  g_signal_connect(lib->gui.button1, "clicked", G_CALLBACK(create_callback), self);
 
   const char *str = dt_conf_get_string_const("plugins/session/jobcode");
   gtk_entry_set_text(lib->gui.entry1, str);
diff --git a/src/libs/snapshots.c b/src/libs/snapshots.c
index ae403636dfd0..4dd974295ea9 100644
--- a/src/libs/snapshots.c
+++ b/src/libs/snapshots.c
@@ -577,9 +577,9 @@ static void _init_snapshot_entry(dt_lib_module_t *self,
   /* create snapshot button */
   s->button = gtk_toggle_button_new();
   gtk_widget_set_name(s->button, "snapshot-button");
-  g_signal_connect(G_OBJECT(s->button), "toggled",
+  g_signal_connect(s->button, "toggled",
                    G_CALLBACK(_lib_snapshots_toggled_callback), self);
-  g_signal_connect(G_OBJECT(s->button), "button-press-event",
+  g_signal_connect(s->button, "button-press-event",
                    G_CALLBACK(_lib_button_button_pressed_callback), self);
 
   s->num = gtk_label_new("");
@@ -595,14 +595,14 @@ static void _init_snapshot_entry(dt_lib_module_t *self,
 
   s->entry = gtk_entry_new();
   gtk_widget_set_halign(s->entry, GTK_ALIGN_FILL);
-  g_signal_connect(G_OBJECT(s->entry), "activate",
+  g_signal_connect(s->entry, "activate",
                    G_CALLBACK(_entry_activated_callback), self);
 
   s->restore_button = dtgtk_button_new(dtgtk_cairo_paint_snapshots_restore, CPF_NONE, NULL);
   gtk_widget_set_name(s->restore_button, "non-flat");
   gtk_widget_set_tooltip_text(s->restore_button,
                               _("restore snapshot into current history"));
-  g_signal_connect(G_OBJECT(s->restore_button), "clicked",
+  g_signal_connect(s->restore_button, "clicked",
                    G_CALLBACK(_lib_snapshots_restore_callback), self);
 }
 
@@ -865,7 +865,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_box_pack_start(GTK_BOX(hbox), d->take_button, TRUE, TRUE, 0);
   d->sidebyside_button = dtgtk_togglebutton_new(dtgtk_cairo_paint_lt_mode_culling_dynamic, 0, NULL);
   gtk_box_pack_start(GTK_BOX(hbox), d->sidebyside_button, FALSE, TRUE, 0);
-  g_signal_connect(G_OBJECT(d->sidebyside_button), "clicked",
+  g_signal_connect(d->sidebyside_button, "clicked",
                    G_CALLBACK(_sidebyside_button_clicked), self);
   gtk_widget_set_tooltip_text(GTK_WIDGET(d->sidebyside_button),
                               _("place the snapshot side-by-side / above-below the current image instead of overlaying"));
diff --git a/src/libs/styles.c b/src/libs/styles.c
index 2dbc8aaf3a85..50b6688313a3 100644
--- a/src/libs/styles.c
+++ b/src/libs/styles.c
@@ -734,13 +734,12 @@ static void _import_clicked(GtkWidget *w, dt_lib_styles_t *d)
   g_object_unref(filechooser);
 }
 
-static gboolean _entry_callback(GtkEntry *entry, dt_lib_styles_t *d)
+static void _entry_callback(GtkEntry *entry, dt_lib_styles_t *d)
 {
   _gui_styles_update_view(d);
-  return FALSE;
 }
 
-static gboolean _entry_activated(GtkEntry *entry, dt_lib_styles_t *d)
+static void _entry_activated(GtkEntry *entry, dt_lib_styles_t *d)
 {
   const gchar *name = gtk_entry_get_text(d->entry);
   if(name)
@@ -753,15 +752,12 @@ static gboolean _entry_activated(GtkEntry *entry, dt_lib_styles_t *d)
       dt_control_apply_styles(imgs, styles, duplicate);
     }
   }
-
-  return FALSE;
 }
 
-static gboolean _duplicate_callback(GtkEntry *entry, dt_lib_styles_t *d)
+static void _duplicate_callback(GtkWidget *entry, dt_lib_styles_t *d)
 {
   dt_conf_set_bool("ui_last/styles_create_duplicate",
                    gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(d->duplicate)));
-  return FALSE;
 }
 
 static void _applymode_combobox_changed(GtkWidget *widget, gpointer user_data)
diff --git a/src/libs/tagging.c b/src/libs/tagging.c
index 07055024ed13..4e9e90ac04fa 100644
--- a/src/libs/tagging.c
+++ b/src/libs/tagging.c
@@ -1414,7 +1414,7 @@ static void _pop_menu_attached(GtkWidget *treeview,
     {
       menuitem = gtk_menu_item_new_with_label(_("attach tag to all"));
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_attached_attach_to_all, self);
+                       G_CALLBACK(_pop_menu_attached_attach_to_all), self);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       menuitem = gtk_separator_menu_item_new();
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
@@ -1423,15 +1423,15 @@ static void _pop_menu_attached(GtkWidget *treeview,
 
   menuitem = gtk_menu_item_new_with_label(_("detach tag"));
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
-  g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_attached_detach, self);
+  g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_attached_detach), self);
 
   menuitem = gtk_menu_item_new_with_label(_("find tag"));
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
-  g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_attached_find, self);
+  g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_attached_find), self);
 
   menuitem = gtk_menu_item_new_with_label(_("copy to clipboard"));
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
-  g_signal_connect(menuitem, "activate", (GCallback)_pop_menu_attached_clipboard, self);
+  g_signal_connect(menuitem, "activate", G_CALLBACK(_pop_menu_attached_clipboard), self);
 
   gtk_widget_show_all(GTK_WIDGET(menu));
 
@@ -2494,12 +2494,12 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
     {
       menuitem = gtk_menu_item_new_with_label(_("attach tag"));
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_dictionary_attach_tag, self);
+                       G_CALLBACK(_pop_menu_dictionary_attach_tag), self);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
 
       menuitem = gtk_menu_item_new_with_label(_("detach tag"));
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_dictionary_detach_tag, self);
+                       G_CALLBACK(_pop_menu_dictionary_detach_tag), self);
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
 
       menuitem = gtk_separator_menu_item_new();
@@ -2510,14 +2510,14 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
       menuitem = gtk_menu_item_new_with_label(_("create tag..."));
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_dictionary_create_tag, self);
+                       G_CALLBACK(_pop_menu_dictionary_create_tag), self);
 
       if(tagid)
       {
         menuitem = gtk_menu_item_new_with_label(_("delete tag"));
         gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
         g_signal_connect(menuitem, "activate",
-                         (GCallback)_pop_menu_dictionary_delete_tag, self);
+                         G_CALLBACK(_pop_menu_dictionary_delete_tag), self);
       }
 
       if(gtk_tree_model_iter_children(model, &child, &iter))
@@ -2525,13 +2525,13 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
         menuitem = gtk_menu_item_new_with_label(_("delete node"));
         gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
         g_signal_connect(menuitem, "activate",
-                         (GCallback)_pop_menu_dictionary_delete_node, self);
+                         G_CALLBACK(_pop_menu_dictionary_delete_node), self);
       }
 
       menuitem = gtk_menu_item_new_with_label(_("edit..."));
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_dictionary_edit_tag, self);
+                       G_CALLBACK(_pop_menu_dictionary_edit_tag), self);
     }
 
     if(d->tree_flag)
@@ -2539,7 +2539,7 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
       menuitem = gtk_menu_item_new_with_label(_("change path..."));
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_dictionary_change_path, self);
+                       G_CALLBACK(_pop_menu_dictionary_change_path), self);
     }
 
     if(d->tree_flag && !tagid)
@@ -2550,7 +2550,7 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
       menuitem = gtk_menu_item_new_with_label(_("set as a tag"));
       gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       g_signal_connect(menuitem, "activate",
-                       (GCallback)_pop_menu_dictionary_set_as_tag, self);
+                       G_CALLBACK(_pop_menu_dictionary_set_as_tag), self);
     }
 
     if(!d->suggestion_flag)
@@ -2561,13 +2561,13 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
 
     menuitem = gtk_menu_item_new_with_label(_("copy to entry"));
     g_signal_connect(menuitem, "activate",
-                     (GCallback)_pop_menu_dictionary_copy_tag, self);
+                     G_CALLBACK(_pop_menu_dictionary_copy_tag), self);
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
 
     menuitem = gtk_menu_item_new_with_label(_("copy to clipboard"));
     gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
     g_signal_connect(menuitem, "activate",
-                     (GCallback)_pop_menu_dictionary_clipboard, self);
+                     G_CALLBACK(_pop_menu_dictionary_clipboard), self);
 
     if(d->collection[0])
     {
@@ -2587,14 +2587,14 @@ static void _pop_menu_dictionary(GtkWidget *treeview,
       {
         menuitem = gtk_menu_item_new_with_label(_("go to tag collection"));
         g_signal_connect(menuitem, "activate",
-                         (GCallback)_pop_menu_dictionary_goto_tag_collection, self);
+                         G_CALLBACK(_pop_menu_dictionary_goto_tag_collection), self);
         gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       }
       if(d->collection[0])
       {
         menuitem = gtk_menu_item_new_with_label(_("go back to work"));
         g_signal_connect(menuitem, "activate",
-                         (GCallback)_pop_menu_dictionary_goto_collection_back, self);
+                         G_CALLBACK(_pop_menu_dictionary_goto_collection_back), self);
         gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
       }
     }
@@ -3470,8 +3470,8 @@ void gui_init(dt_lib_module_t *self)
      DT_TAG_SORT_COUNT_ID, (GtkTreeIterCompareFunc)_sort_tree_count_func, self, NULL);
   d->attached_liststore = liststore;
   g_object_set(G_OBJECT(view), "has-tooltip", TRUE, NULL);
-  g_signal_connect(G_OBJECT(view), "query-tooltip",
-                   G_CALLBACK(_row_tooltip_setup), (gpointer)self);
+  g_signal_connect(view, "query-tooltip",
+                   G_CALLBACK(_row_tooltip_setup), self);
 
   col = gtk_tree_view_column_new();
   gtk_tree_view_append_column(view, col);
@@ -3487,7 +3487,7 @@ void gui_init(dt_lib_module_t *self)
   gtk_tree_view_column_pack_start(col, renderer, TRUE);
   gtk_tree_view_column_set_cell_data_func(col, renderer,
                                           _tree_tagname_show_attached,
-                                          (gpointer)self, NULL);
+                                          self, NULL);
 
   gtk_tree_selection_set_mode(gtk_tree_view_get_selection(view), GTK_SELECTION_SINGLE);
   gtk_tree_view_set_model(view, GTK_TREE_MODEL(liststore));
@@ -3498,10 +3498,10 @@ void gui_init(dt_lib_module_t *self)
        "\npress Delete or double-click to detach"
        "\nright-click for other actions on attached tag,"
        "\nTab to give the focus to entry"));
-  g_signal_connect(G_OBJECT(view), "button-press-event",
-                   G_CALLBACK(_click_on_view_attached), (gpointer)self);
-  g_signal_connect(G_OBJECT(view), "key-press-event",
-                   G_CALLBACK(_attached_key_pressed), (gpointer)self);
+  g_signal_connect(view, "button-press-event",
+                   G_CALLBACK(_click_on_view_attached), self);
+  g_signal_connect(view, "key-press-event",
+                   G_CALLBACK(_attached_key_pressed), self);
   g_signal_connect(gtk_tree_view_get_selection(view), "changed",
                    G_CALLBACK(_tree_selection_changed), self);
 
@@ -3524,7 +3524,7 @@ void gui_init(dt_lib_module_t *self)
   button = dtgtk_togglebutton_new(paint, 0, NULL);                           \
   gtk_widget_set_tooltip_text(button, tooltip);                              \
   gtk_box_pack_end(hbox, button, FALSE, TRUE, 0);                            \
-  g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(callback), self); \
+  g_signal_connect(button, "clicked", G_CALLBACK(callback), self);           \
   dt_action_define(toggle, NULL, action, button, &dt_action_def_toggle);
 
   d->toggle_hide_button = NEW_TOGGLE_BUTTON
@@ -3558,17 +3558,17 @@ void gui_init(dt_lib_module_t *self)
        "\npress shift+Tab to select the first attached user tag"));
   gtk_box_pack_start(hbox, w, TRUE, TRUE, 0);
   gtk_widget_add_events(GTK_WIDGET(w), GDK_KEY_RELEASE_MASK);
-  g_signal_connect(G_OBJECT(w), "changed",
-                   G_CALLBACK(_tag_name_changed), (gpointer)self);
-  g_signal_connect(G_OBJECT(w), "key-press-event",
-                   G_CALLBACK(_enter_key_pressed), (gpointer)self);
+  g_signal_connect(w, "changed",
+                   G_CALLBACK(_tag_name_changed), self);
+  g_signal_connect(w, "key-press-event",
+                   G_CALLBACK(_enter_key_pressed), self);
   d->entry = GTK_ENTRY(w);
 
   button = dtgtk_button_new(dtgtk_cairo_paint_multiply_small, 0, NULL);
   gtk_widget_set_tooltip_text(button, _("clear entry"));
   gtk_box_pack_end(hbox, button, FALSE, TRUE, 0);
-  g_signal_connect(G_OBJECT(button), "clicked",
-                   G_CALLBACK(_clear_entry_button_callback), (gpointer)self);
+  g_signal_connect(button, "clicked",
+                   G_CALLBACK(_clear_entry_button_callback), self);
   gtk_box_pack_start(box, GTK_WIDGET(hbox), FALSE, TRUE, 0);
   dt_gui_add_class(GTK_WIDGET(box), "dt_spacing_sw");
   d->clear_button = button;
@@ -3625,7 +3625,7 @@ void gui_init(dt_lib_module_t *self)
   g_object_set(renderer, "ellipsize", PANGO_ELLIPSIZE_MIDDLE, (gchar *)0);
   gtk_tree_view_column_pack_start(col, renderer, TRUE);
   gtk_tree_view_column_set_cell_data_func(col, renderer,
-                                          _tree_tagname_show_dictionary, (gpointer)self, NULL);
+                                          _tree_tagname_show_dictionary, self, NULL);
   gtk_tree_view_set_expander_column(view, col);
 
   gtk_tree_selection_set_mode(gtk_tree_view_get_selection(view), GTK_SELECTION_SINGLE);
@@ -3638,15 +3638,15 @@ void gui_init(dt_lib_module_t *self)
        "\nright-click for other actions on selected tag"
        "\nshift+Tab to give the focus to entry"));
 
-  g_signal_connect(G_OBJECT(view), "button-press-event",
-                   G_CALLBACK(_click_on_view_dictionary), (gpointer)self);
-  g_signal_connect(G_OBJECT(view), "key-press-event",
-                   G_CALLBACK(_dictionary_key_pressed), (gpointer)self);
+  g_signal_connect(view, "button-press-event",
+                   G_CALLBACK(_click_on_view_dictionary), self);
+  g_signal_connect(view, "key-press-event",
+                   G_CALLBACK(_dictionary_key_pressed), self);
   gtk_tree_view_set_model(view, GTK_TREE_MODEL(d->dictionary_listfilter));
   g_object_unref(d->dictionary_listfilter);
   g_object_set(G_OBJECT(view), "has-tooltip", TRUE, NULL);
-  g_signal_connect(G_OBJECT(view), "query-tooltip",
-                   G_CALLBACK(_row_tooltip_setup), (gpointer)self);
+  g_signal_connect(view, "query-tooltip",
+                   G_CALLBACK(_row_tooltip_setup), self);
   g_signal_connect(gtk_tree_view_get_selection(view), "changed",
                    G_CALLBACK(_tree_selection_changed), self);
 
@@ -3848,7 +3848,7 @@ static void _lib_tagging_tag_show(dt_action_t *action)
   gtk_entry_completion_set_text_column(completion, DT_LIB_TAGGING_COL_PATH);
   gtk_entry_completion_set_inline_completion(completion, TRUE);
   gtk_entry_completion_set_popup_set_width(completion, FALSE);
-  g_signal_connect(G_OBJECT(completion), "match-selected",
+  g_signal_connect(completion, "match-selected",
                    G_CALLBACK(_match_selected_func), self);
   gtk_entry_completion_set_match_func(completion, _completion_match_func, NULL, NULL);
   gtk_entry_set_completion(GTK_ENTRY(entry), completion);
@@ -3967,7 +3967,7 @@ void _menuitem_preferences(GtkMenuItem *menuitem,
 void set_preferences(void *menu, dt_lib_module_t *self)
 {
   GtkWidget *mi = gtk_menu_item_new_with_label(_("preferences..."));
-  g_signal_connect(G_OBJECT(mi), "activate", G_CALLBACK(_menuitem_preferences), self);
+  g_signal_connect(mi, "activate", G_CALLBACK(_menuitem_preferences), self);
   gtk_menu_shell_append(GTK_MENU_SHELL(menu), mi);
 }
 
diff --git a/src/libs/tools/colorlabels.c b/src/libs/tools/colorlabels.c
index 2c6831bd627e..2448a08004a0 100644
--- a/src/libs/tools/colorlabels.c
+++ b/src/libs/tools/colorlabels.c
@@ -44,9 +44,9 @@ typedef struct dt_lib_colorlabels_t
 } dt_lib_colorlabels_t;
 
 /* callback when a colorlabel button is clicked */
-static void _lib_colorlabels_button_clicked_callback(GtkWidget *w,
-                                                     GdkEventButton *event,
-                                                     dt_lib_module_t *self);
+static gboolean _lib_colorlabels_button_clicked_callback(GtkWidget *w,
+                                                         GdkEventButton *event,
+                                                         dt_lib_module_t *self);
 
 gint _get_colorlabel(dt_lib_module_t *self, GtkWidget *w)
 {
@@ -136,10 +136,10 @@ void gui_init(dt_lib_module_t *self)
     gtk_widget_set_tooltip_markup(button, tooltip);
     g_free(tooltip);
     gtk_box_pack_start(GTK_BOX(self->widget), button, TRUE, TRUE, 0);
-    g_signal_connect(G_OBJECT(button), "button-press-event",
+    g_signal_connect(button, "button-press-event",
                      G_CALLBACK(_lib_colorlabels_button_clicked_callback),
                      self);
-    g_signal_connect(G_OBJECT(button), "enter-notify-event",
+    g_signal_connect(button, "enter-notify-event",
                      G_CALLBACK(_lib_colorlabels_enter_notify_callback),
                      self);
     ac = dt_action_define(&darktable.control->actions_thumb, NULL,
@@ -267,9 +267,9 @@ static void _lib_colorlabels_edit(dt_lib_module_t *self,
   }
 }
 
-static void _lib_colorlabels_button_clicked_callback(GtkWidget *w,
-                                                     GdkEventButton *event,
-                                                     dt_lib_module_t *self)
+static gboolean _lib_colorlabels_button_clicked_callback(GtkWidget *w,
+                                                         GdkEventButton *event,
+                                                         dt_lib_module_t *self)
 {
   dt_lib_colorlabels_t *d = self->data;
 
@@ -290,6 +290,7 @@ static void _lib_colorlabels_button_clicked_callback(GtkWidget *w,
                                DT_COLLECTION_CHANGE_RELOAD, DT_COLLECTION_PROP_COLORLABEL,
                                imgs);
   }
+  return TRUE;
 }
 
 // clang-format off
diff --git a/src/libs/tools/darktable.c b/src/libs/tools/darktable.c
index 720c527b8e66..5073eb6ba08f 100644
--- a/src/libs/tools/darktable.c
+++ b/src/libs/tools/darktable.c
@@ -94,9 +94,9 @@ void gui_init(dt_lib_module_t *self)
   self->widget = gtk_event_box_new();
 
   /* connect callbacks */
-  g_signal_connect(G_OBJECT(self->widget), "draw",
+  g_signal_connect(self->widget, "draw",
                    G_CALLBACK(_lib_darktable_draw_callback), self);
-  g_signal_connect(G_OBJECT(self->widget), "button-press-event",
+  g_signal_connect(self->widget, "button-press-event",
                    G_CALLBACK(_lib_darktable_button_press_callback), self);
 
   /* create a cairo surface of dt icon */
diff --git a/src/libs/tools/filmstrip.c b/src/libs/tools/filmstrip.c
index e8178a1a9d58..399463ecbd60 100644
--- a/src/libs/tools/filmstrip.c
+++ b/src/libs/tools/filmstrip.c
@@ -91,7 +91,7 @@ void gui_init(dt_lib_module_t *self)
   self->widget = gtk_event_box_new();
 
   /* connect callbacks */
-  g_signal_connect(G_OBJECT(self->widget), "draw",
+  g_signal_connect(self->widget, "draw",
                    G_CALLBACK(_lib_filmstrip_draw_callback), self);
 
   /* initialize view manager proxy */
diff --git a/src/libs/tools/filter.c b/src/libs/tools/filter.c
index 6ab6c4ca1efd..57c91de28bd3 100644
--- a/src/libs/tools/filter.c
+++ b/src/libs/tools/filter.c
@@ -102,7 +102,7 @@ void gui_init(dt_lib_module_t *self)
 
   GtkWidget *bt = dtgtk_button_new(dtgtk_cairo_paint_filtering_menu, 0, NULL);
   gtk_widget_set_tooltip_text(bt, _("filter preferences"));
-  g_signal_connect(G_OBJECT(bt), "button-press-event", G_CALLBACK(_pref_show), self);
+  g_signal_connect(bt, "button-press-event", G_CALLBACK(_pref_show), self);
   gtk_box_pack_start(GTK_BOX(self->widget), bt, FALSE, TRUE, 0);
 
   d->filter_box = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0);
diff --git a/src/libs/tools/global_toolbox.c b/src/libs/tools/global_toolbox.c
index 5ab5b172282c..ac31640c2a5a 100644
--- a/src/libs/tools/global_toolbox.c
+++ b/src/libs/tools/global_toolbox.c
@@ -393,7 +393,7 @@ void gui_init(dt_lib_module_t *self)
   else
     gtk_widget_set_tooltip_text(d->grouping_button, _("collapse grouped images"));
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(d->grouping_button), darktable.gui->grouping);
-  g_signal_connect(G_OBJECT(d->grouping_button), "clicked", G_CALLBACK(_lib_filter_grouping_button_clicked),
+  g_signal_connect(d->grouping_button, "clicked", G_CALLBACK(_lib_filter_grouping_button_clicked),
                    NULL);
 
   /* create the "show/hide overlays" button */
@@ -403,18 +403,18 @@ void gui_init(dt_lib_module_t *self)
   d->over_popup = gtk_popover_new(d->overlays_button);
   gtk_widget_set_size_request(d->over_popup, 350, -1);
   g_object_set(G_OBJECT(d->over_popup), "transitions-enabled", FALSE, NULL);
-  g_signal_connect(G_OBJECT(d->overlays_button), "clicked", G_CALLBACK(_overlays_show_popup), self);
+  g_signal_connect(d->overlays_button, "clicked", G_CALLBACK(_overlays_show_popup), self);
   // we register size of overlay icon to keep in sync thumbtable overlays
-  g_signal_connect(G_OBJECT(d->overlays_button), "size-allocate", G_CALLBACK(_main_icons_register_size), NULL);
+  g_signal_connect(d->overlays_button, "size-allocate", G_CALLBACK(_main_icons_register_size), NULL);
 
   GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
 
   gtk_container_add(GTK_CONTAINER(d->over_popup), vbox);
 
-#define NEW_RADIO(widget, box, callback, label)                                               \
+#define NEW_RADIO(widget, box, callback, label)                                     \
   rb = gtk_radio_button_new_with_label_from_widget(GTK_RADIO_BUTTON(rb), _(label)); \
   dt_action_define(ac, NULL, label, rb, &dt_action_def_button);                     \
-  g_signal_connect(G_OBJECT(rb), "clicked", G_CALLBACK(callback), self);            \
+  g_signal_connect(rb, "clicked", G_CALLBACK(callback), self);                      \
   gtk_box_pack_start(GTK_BOX(box), rb, TRUE, TRUE, 0);                              \
   widget = rb;
 
@@ -437,11 +437,11 @@ void gui_init(dt_lib_module_t *self)
   NEW_RADIO(d->over_r6, hbox, _overlays_toggle_button, N_("overlays block on mouse hover"));
   gtk_box_pack_start(GTK_BOX(hbox), gtk_label_new(_("during (s)")), FALSE, FALSE, 0);
   d->over_timeout = gtk_spin_button_new_with_range(-1, 99, 1);
-  g_signal_connect(G_OBJECT(d->over_timeout), "value-changed", G_CALLBACK(_overlays_timeout_changed), self);
+  g_signal_connect(d->over_timeout, "value-changed", G_CALLBACK(_overlays_timeout_changed), self);
   gtk_box_pack_start(GTK_BOX(hbox), d->over_timeout, TRUE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(d->thumbnails_box), hbox, TRUE, TRUE, 0);
   d->over_tt = gtk_check_button_new_with_label(_("show tooltip"));
-  g_signal_connect(G_OBJECT(d->over_tt), "toggled", G_CALLBACK(_overlays_toggle_button), self);
+  g_signal_connect(d->over_tt, "toggled", G_CALLBACK(_overlays_toggle_button), self);
   gtk_widget_set_name(d->over_tt, "show-tooltip");
   gtk_box_pack_start(GTK_BOX(d->thumbnails_box), d->over_tt, TRUE, TRUE, 0);
 
@@ -463,11 +463,11 @@ void gui_init(dt_lib_module_t *self)
   NEW_RADIO(d->over_culling_r6, hbox, _overlays_toggle_culling_button, N_("overlays block on mouse hover"));
   gtk_box_pack_start(GTK_BOX(hbox), gtk_label_new(_("during (s)")), FALSE, FALSE, 0);
   d->over_culling_timeout = gtk_spin_button_new_with_range(-1, 99, 1);
-  g_signal_connect(G_OBJECT(d->over_culling_timeout), "value-changed", G_CALLBACK(_overlays_timeout_changed), self);
+  g_signal_connect(d->over_culling_timeout, "value-changed", G_CALLBACK(_overlays_timeout_changed), self);
   gtk_box_pack_start(GTK_BOX(hbox), d->over_culling_timeout, TRUE, TRUE, 0);
   gtk_box_pack_start(GTK_BOX(d->culling_box), hbox, TRUE, TRUE, 0);
   d->over_culling_tt = gtk_check_button_new_with_label(_("show tooltip"));
-  g_signal_connect(G_OBJECT(d->over_culling_tt), "toggled", G_CALLBACK(_overlays_toggle_culling_button), self);
+  g_signal_connect(d->over_culling_tt, "toggled", G_CALLBACK(_overlays_toggle_culling_button), self);
   gtk_widget_set_name(d->over_culling_tt, "show-tooltip");
   gtk_box_pack_start(GTK_BOX(d->culling_box), d->over_culling_tt, TRUE, TRUE, 0);
 
@@ -480,7 +480,7 @@ void gui_init(dt_lib_module_t *self)
   d->help_button = dtgtk_togglebutton_new(dtgtk_cairo_paint_help, 0, NULL);
   dt_action_define(&darktable.control->actions_global, NULL, N_("help"), d->help_button, &dt_action_def_toggle);
   gtk_widget_set_tooltip_text(d->help_button, _("enable this, then click on a control element to see its online help"));
-  g_signal_connect(G_OBJECT(d->help_button), "clicked", G_CALLBACK(_lib_help_button_clicked), d);
+  g_signal_connect(d->help_button, "clicked", G_CALLBACK(_lib_help_button_clicked), d);
 
   /* create the shortcuts button */
   d->keymap_button = dtgtk_togglebutton_new(dtgtk_cairo_paint_shortcut, 0, NULL);
@@ -500,9 +500,9 @@ void gui_init(dt_lib_module_t *self)
                                                   "dialog for more detailed configuration\n"
                                                   "\n"
                                                   "right-click to exit mapping mode"));
-  g_signal_connect(G_OBJECT(d->keymap_button), "clicked", G_CALLBACK(_lib_keymap_button_clicked), d);
-  g_signal_connect(G_OBJECT(d->keymap_button), "button-press-event", G_CALLBACK(_lib_keymap_button_press_release), d);
-  g_signal_connect(G_OBJECT(d->keymap_button), "button-release-event", G_CALLBACK(_lib_keymap_button_press_release), d);
+  g_signal_connect(d->keymap_button, "clicked", G_CALLBACK(_lib_keymap_button_clicked), d);
+  g_signal_connect(d->keymap_button, "button-press-event", G_CALLBACK(_lib_keymap_button_press_release), d);
+  g_signal_connect(d->keymap_button, "button-release-event", G_CALLBACK(_lib_keymap_button_press_release), d);
 
   // the rest of these is added in reverse order as they are always put at the end of the container.
   // that's done so that buttons added via Lua will come first.
@@ -511,7 +511,7 @@ void gui_init(dt_lib_module_t *self)
   d->preferences_button = dtgtk_button_new(dtgtk_cairo_paint_preferences, 0, NULL);
   ac = dt_action_define(&darktable.control->actions_global, NULL, N_("preferences"), d->preferences_button, &dt_action_def_button);
   gtk_widget_set_tooltip_text(d->preferences_button, _("show global preferences"));
-  g_signal_connect(G_OBJECT(d->preferences_button), "clicked", G_CALLBACK(_lib_preferences_button_clicked),
+  g_signal_connect(d->preferences_button, "clicked", G_CALLBACK(_lib_preferences_button_clicked),
                    NULL);
 
   // Register CMD+, for preferences (this is standard on macOS)
@@ -573,7 +573,7 @@ static void _main_do_event_help(GdkEvent *event, gpointer data)
         if(event_widget == d->help_button)
           break;
 
-        dt_gui_show_help(event_widget);
+        dt_gui_show_help(event_widget, NULL);
       }
       handled = TRUE;
       break;
@@ -670,7 +670,7 @@ static void _show_shortcuts_prefs(GtkWidget *w)
     gtk_window_move(GTK_WINDOW(shortcuts_dialog), _shortcuts_dialog_posize.x, _shortcuts_dialog_posize.y);
     gtk_window_resize(GTK_WINDOW(shortcuts_dialog), _shortcuts_dialog_posize.w, _shortcuts_dialog_posize.h);
   }
-  g_signal_connect(G_OBJECT(shortcuts_dialog), "configure-event", G_CALLBACK(_resize_shortcuts_dialog), NULL);
+  g_signal_connect(shortcuts_dialog, "configure-event", G_CALLBACK(_resize_shortcuts_dialog), NULL);
 
   //grab the content area of the dialog
   dt_gui_dialog_add(GTK_DIALOG(shortcuts_dialog), dt_shortcuts_prefs(w));
diff --git a/src/libs/tools/lighttable.c b/src/libs/tools/lighttable.c
index f5a8b09bd51f..4cd3ca2bb154 100644
--- a/src/libs/tools/lighttable.c
+++ b/src/libs/tools/lighttable.c
@@ -461,7 +461,7 @@ void gui_init(dt_lib_module_t *self)
   dt_action_register(ac, NULL, _lib_lighttable_key_accel_toggle_filemanager, 0, 0);
   dt_gui_add_help_link(d->layout_filemanager, "layout_filemanager");
   gtk_widget_set_tooltip_text(d->layout_filemanager, _("click to enter filemanager layout."));
-  g_signal_connect(G_OBJECT(d->layout_filemanager), "button-release-event",
+  g_signal_connect(d->layout_filemanager, "button-release-event",
                    G_CALLBACK(_lib_lighttable_layout_btn_release), self);
 
   d->layout_zoomable = dtgtk_togglebutton_new(dtgtk_cairo_paint_lt_mode_zoom, 0, NULL);
@@ -469,7 +469,7 @@ void gui_init(dt_lib_module_t *self)
   dt_action_register(ac, NULL, _lib_lighttable_key_accel_toggle_zoomable, 0, 0);
   dt_gui_add_help_link(d->layout_zoomable, "layout_zoomable");
   gtk_widget_set_tooltip_text(d->layout_zoomable, _("click to enter zoomable lighttable layout."));
-  g_signal_connect(G_OBJECT(d->layout_zoomable), "button-release-event",
+  g_signal_connect(d->layout_zoomable, "button-release-event",
                    G_CALLBACK(_lib_lighttable_layout_btn_release), self);
 
   d->layout_culling_fix = dtgtk_togglebutton_new(dtgtk_cairo_paint_lt_mode_culling_fixed, 0, NULL);
@@ -477,14 +477,14 @@ void gui_init(dt_lib_module_t *self)
   dt_shortcut_register(ac, DT_ACTION_ELEMENT_DEFAULT, DT_ACTION_EFFECT_HOLD_TOGGLE, GDK_KEY_x, 0);
   dt_shortcut_register(ac, DT_ACTION_ELEMENT_CULLING_NO_RESTRICTION, DT_ACTION_EFFECT_HOLD_TOGGLE, GDK_KEY_x, GDK_SHIFT_MASK);
   dt_gui_add_help_link(d->layout_culling_fix, "layout_culling");
-  g_signal_connect(G_OBJECT(d->layout_culling_fix), "button-release-event",
+  g_signal_connect(d->layout_culling_fix, "button-release-event",
                    G_CALLBACK(_lib_lighttable_layout_btn_release), self);
 
   d->layout_culling_dynamic = dtgtk_togglebutton_new(dtgtk_cairo_paint_lt_mode_culling_dynamic, 0, NULL);
   ac = dt_action_define(ltv, NULL, N_("toggle culling dynamic mode"), d->layout_culling_dynamic, NULL);
   dt_action_register(ac, NULL, _lib_lighttable_key_accel_toggle_culling_dynamic_mode, GDK_KEY_x, GDK_CONTROL_MASK);
   dt_gui_add_help_link(d->layout_culling_dynamic, "layout_culling");
-  g_signal_connect(G_OBJECT(d->layout_culling_dynamic), "button-release-event",
+  g_signal_connect(d->layout_culling_dynamic, "button-release-event",
                    G_CALLBACK(_lib_lighttable_layout_btn_release), self);
 
   d->layout_preview = dtgtk_togglebutton_new(dtgtk_cairo_paint_lt_mode_fullpreview, 0, NULL);
@@ -494,7 +494,7 @@ void gui_init(dt_lib_module_t *self)
   dt_shortcut_register(ac, DT_ACTION_ELEMENT_DEFAULT, DT_ACTION_EFFECT_HOLD, GDK_KEY_w, 0);
   dt_shortcut_register(ac, DT_ACTION_ELEMENT_PREVIEW_FOCUS_DETECT, DT_ACTION_EFFECT_HOLD, GDK_KEY_w, GDK_CONTROL_MASK);
   dt_gui_add_help_link(d->layout_preview, "layout_preview");
-  g_signal_connect(G_OBJECT(d->layout_preview), "button-release-event",
+  g_signal_connect(d->layout_preview, "button-release-event",
                    G_CALLBACK(_lib_lighttable_layout_btn_release), self);
 
   d->layout_box = dt_gui_hbox(d->layout_filemanager, d->layout_zoomable,
@@ -516,14 +516,14 @@ void gui_init(dt_lib_module_t *self)
   dt_action_register(ac, NULL, _lib_lighttable_key_accel_toggle_restricted_mode, GDK_KEY_r, GDK_CONTROL_MASK);
   dt_gui_add_help_link(d->layout_culling_restricted, "layout_culling");
   gtk_widget_set_no_show_all(d->layout_culling_restricted, TRUE);
-  g_signal_connect(G_OBJECT(d->layout_culling_restricted), "button-release-event",
+  g_signal_connect(d->layout_culling_restricted, "button-release-event",
                    G_CALLBACK(_lib_lighttable_restricted_btn_release), self);
 
   self->widget = dt_gui_hbox(d->layout_box, d->zoom, d->layout_culling_restricted);
 
   _lib_lighttable_update_btn(self);
 
-  g_signal_connect(G_OBJECT(d->zoom), "value-changed", G_CALLBACK(_lib_lighttable_zoom_slider_changed), self);
+  g_signal_connect(d->zoom, "value-changed", G_CALLBACK(_lib_lighttable_zoom_slider_changed), self);
 
   darktable.view_manager->proxy.lighttable.module = self;
   darktable.view_manager->proxy.lighttable.set_zoom = _lib_lighttable_set_zoom;
diff --git a/src/libs/tools/ratings.c b/src/libs/tools/ratings.c
index e5fe913bbd4f..c2e656ca9081 100644
--- a/src/libs/tools/ratings.c
+++ b/src/libs/tools/ratings.c
@@ -96,12 +96,12 @@ void gui_init(dt_lib_module_t *self)
   /* connect callbacks */
   gtk_widget_set_tooltip_text(drawing, _("set star rating for selected images"));
   gtk_widget_set_app_paintable(drawing, TRUE);
-  g_signal_connect(G_OBJECT(drawing), "draw", G_CALLBACK(_lib_ratings_draw_callback), self);
-  g_signal_connect(G_OBJECT(drawing), "button-press-event", G_CALLBACK(_lib_ratings_button_press_callback), self);
-  g_signal_connect(G_OBJECT(drawing), "button-release-event", G_CALLBACK(_lib_ratings_button_release_callback),
+  g_signal_connect(drawing, "draw", G_CALLBACK(_lib_ratings_draw_callback), self);
+  g_signal_connect(drawing, "button-press-event", G_CALLBACK(_lib_ratings_button_press_callback), self);
+  g_signal_connect(drawing, "button-release-event", G_CALLBACK(_lib_ratings_button_release_callback),
                    self);
-  g_signal_connect(G_OBJECT(drawing), "motion-notify-event", G_CALLBACK(_lib_ratings_motion_notify_callback), self);
-  g_signal_connect(G_OBJECT(drawing), "leave-notify-event", G_CALLBACK(_lib_ratings_leave_notify_callback), self);
+  g_signal_connect(drawing, "motion-notify-event", G_CALLBACK(_lib_ratings_motion_notify_callback), self);
+  g_signal_connect(drawing, "leave-notify-event", G_CALLBACK(_lib_ratings_leave_notify_callback), self);
 
   gtk_box_pack_start(GTK_BOX(self->widget), drawing, TRUE, TRUE, 0);
 
diff --git a/src/libs/tools/timeline.c b/src/libs/tools/timeline.c
index 240472f884f9..5f9947f1ce98 100644
--- a/src/libs/tools/timeline.c
+++ b/src/libs/tools/timeline.c
@@ -1399,15 +1399,15 @@ void gui_init(dt_lib_module_t *self)
                                          | GDK_BUTTON_RELEASE_MASK | darktable.gui->scroll_mask
                                          | GDK_LEAVE_NOTIFY_MASK);
 
-  g_signal_connect(G_OBJECT(d->timeline), "draw", G_CALLBACK(_lib_timeline_draw_callback), self);
-  g_signal_connect(G_OBJECT(d->timeline), "button-press-event", G_CALLBACK(_lib_timeline_button_press_callback),
+  g_signal_connect(d->timeline, "draw", G_CALLBACK(_lib_timeline_draw_callback), self);
+  g_signal_connect(d->timeline, "button-press-event", G_CALLBACK(_lib_timeline_button_press_callback),
                    self);
-  g_signal_connect(G_OBJECT(d->timeline), "button-release-event",
+  g_signal_connect(d->timeline, "button-release-event",
                    G_CALLBACK(_lib_timeline_button_release_callback), self);
-  g_signal_connect(G_OBJECT(d->timeline), "scroll-event", G_CALLBACK(_lib_timeline_scroll_callback), self);
-  g_signal_connect(G_OBJECT(d->timeline), "motion-notify-event", G_CALLBACK(_lib_timeline_motion_notify_callback),
+  g_signal_connect(d->timeline, "scroll-event", G_CALLBACK(_lib_timeline_scroll_callback), self);
+  g_signal_connect(d->timeline, "motion-notify-event", G_CALLBACK(_lib_timeline_motion_notify_callback),
                    self);
-  g_signal_connect(G_OBJECT(d->timeline), "leave-notify-event", G_CALLBACK(_lib_timeline_mouse_leave_callback),
+  g_signal_connect(d->timeline, "leave-notify-event", G_CALLBACK(_lib_timeline_mouse_leave_callback),
                    self);
 
   gtk_box_pack_start(GTK_BOX(self->widget), d->timeline, TRUE, TRUE, 0);
diff --git a/src/libs/tools/viewswitcher.c b/src/libs/tools/viewswitcher.c
index c6743058d7a8..9a185e212b30 100644
--- a/src/libs/tools/viewswitcher.c
+++ b/src/libs/tools/viewswitcher.c
@@ -82,7 +82,7 @@ int position(const dt_lib_module_t *self)
 
 #define SHORTCUT_TOOLTIP(v, w) dt_action_define(&darktable.control->actions_global, "switch views", v->module_name, w, NULL);
 
-static void _dropdown_changed(GtkComboBox *widget, dt_lib_viewswitcher_t *d)
+static void _dropdown_changed(GtkWidget *widget, dt_lib_viewswitcher_t *d)
 {
   GtkTreeIter iter;
   if(gtk_combo_box_get_active_iter(GTK_COMBO_BOX(d->dropdown), &iter))
@@ -151,7 +151,7 @@ void gui_init(dt_lib_module_t *self)
         gtk_list_store_insert_with_values(model, NULL, -1, TEXT_COLUMN, _("other"), VIEW_COLUMN, NULL, SENSITIVE_COLUMN, 0, -1);
 
         gtk_box_pack_start(GTK_BOX(self->widget), d->dropdown, FALSE, FALSE, 0);
-        g_signal_connect(G_OBJECT(d->dropdown), "changed", G_CALLBACK(_dropdown_changed), d);
+        g_signal_connect(d->dropdown, "changed", G_CALLBACK(_dropdown_changed), d);
       }
 
       gtk_list_store_insert_with_values(model, NULL, -1, TEXT_COLUMN, view->name(view), VIEW_COLUMN, view, SENSITIVE_COLUMN, gimping ? 0 : 1, -1);
@@ -258,13 +258,13 @@ static GtkWidget *_lib_viewswitcher_create_label(dt_view_t *view)
   gtk_widget_set_state_flags(b, GTK_STATE_FLAG_NORMAL, TRUE);
 
   /* connect button press handler */
-  g_signal_connect(G_OBJECT(eb), "button-press-event", G_CALLBACK(_lib_viewswitcher_button_press_callback), view);
+  g_signal_connect(eb, "button-press-event", G_CALLBACK(_lib_viewswitcher_button_press_callback), view);
 
   /* set enter/leave notify events and connect signals */
   gtk_widget_add_events(GTK_WIDGET(eb), GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
 
-  g_signal_connect(G_OBJECT(eb), "enter-notify-event", G_CALLBACK(_lib_viewswitcher_enter_leave_notify_callback), b);
-  g_signal_connect(G_OBJECT(eb), "leave-notify-event", G_CALLBACK(_lib_viewswitcher_enter_leave_notify_callback), b);
+  g_signal_connect(eb, "enter-notify-event", G_CALLBACK(_lib_viewswitcher_enter_leave_notify_callback), b);
+  g_signal_connect(eb, "leave-notify-event", G_CALLBACK(_lib_viewswitcher_enter_leave_notify_callback), b);
 
   return eb;
 }
diff --git a/src/lua/preferences.c b/src/lua/preferences.c
index b198f0588f44..bf3df7a0b043 100644
--- a/src/lua/preferences.c
+++ b/src/lua/preferences.c
@@ -501,8 +501,8 @@ static void update_widget_enum(pref_element* cur_elt, GtkWidget* dialog, GtkWidg
 {
   char pref_name[1024];
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_enum), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_enum), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_enum), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_enum), cur_elt);
   gtk_combo_box_set_active(GTK_COMBO_BOX(cur_elt->widget), 0);
   const char *value = dt_conf_get_string_const(pref_name);
   do {
@@ -533,8 +533,8 @@ static void update_widget_dir(pref_element* cur_elt, GtkWidget* dialog, GtkWidge
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
   const char *str = dt_conf_get_string_const(pref_name);
   gtk_file_chooser_set_filename(GTK_FILE_CHOOSER(cur_elt->widget), str);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_dir), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_dir), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_dir), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_dir), cur_elt);
 }
 
 
@@ -544,8 +544,8 @@ static void update_widget_file(pref_element* cur_elt, GtkWidget* dialog, GtkWidg
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
   const char *str = dt_conf_get_string_const(pref_name);
   gtk_file_chooser_set_filename(GTK_FILE_CHOOSER(cur_elt->widget), str);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_file), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_file), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_file), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_file), cur_elt);
 }
 
 
@@ -553,8 +553,8 @@ static void update_widget_string(pref_element* cur_elt, GtkWidget* dialog, GtkWi
 {
   char pref_name[1024];
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_string), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_string), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_string), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_string), cur_elt);
   const char *str = dt_conf_get_string_const(pref_name);
   gtk_entry_set_text(GTK_ENTRY(cur_elt->widget), str);
 }
@@ -564,8 +564,8 @@ static void update_widget_bool(pref_element* cur_elt, GtkWidget* dialog, GtkWidg
 {
   char pref_name[1024];
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(click_widget_bool), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_bool), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(click_widget_bool), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_bool), cur_elt);
   gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(cur_elt->widget), dt_conf_get_bool(pref_name));
 }
 
@@ -575,8 +575,8 @@ static void update_widget_int(pref_element* cur_elt, GtkWidget* dialog, GtkWidge
   char pref_name[1024];
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(cur_elt->widget), dt_conf_get_int(pref_name));
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_int), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_int), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_int), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_int), cur_elt);
 }
 
 
@@ -585,8 +585,8 @@ static void update_widget_float(pref_element* cur_elt, GtkWidget* dialog, GtkWid
   char pref_name[1024];
   get_pref_name(pref_name, sizeof(pref_name), cur_elt->script, cur_elt->name);
   gtk_spin_button_set_value(GTK_SPIN_BUTTON(cur_elt->widget), dt_conf_get_float(pref_name));
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_float), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_float), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_float), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_float), cur_elt);
 }
 
 
@@ -599,8 +599,8 @@ static void update_widget_lua(pref_element* cur_elt, GtkWidget* dialog, GtkWidge
   lua_pushstring(L, "reset");
   lua_call(L, 2, 0);
   dt_lua_unlock();
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(reset_widget_lua), cur_elt);
-  g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(response_callback_lua), cur_elt);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(reset_widget_lua), cur_elt);
+  g_signal_connect(dialog, "response", G_CALLBACK(response_callback_lua), cur_elt);
 }
 
 
diff --git a/src/lua/widget/container.c b/src/lua/widget/container.c
index ec5045d025b0..4f5e3bd959af 100644
--- a/src/lua/widget/container.c
+++ b/src/lua/widget/container.c
@@ -49,7 +49,7 @@ static int container_reset(lua_State* L)
   return 0;
 }
 
-static void on_child_added(GtkContainer *container,GtkWidget *child,lua_container user_data)
+static void on_child_added(GtkWidget *container,GtkWidget *child,lua_container user_data)
 {
   dt_lua_async_call_alien(dt_lua_widget_trigger_callback,
       0,NULL,NULL,
@@ -59,7 +59,7 @@ static void on_child_added(GtkContainer *container,GtkWidget *child,lua_containe
       LUA_ASYNC_DONE);
 }
 
-static void on_child_removed(GtkContainer *container,GtkWidget *child,lua_container user_data)
+static void on_child_removed(GtkWidget *container,GtkWidget *child,lua_container user_data)
 {
   dt_lua_async_call_alien(dt_lua_widget_trigger_callback,
       0,NULL,NULL,
diff --git a/src/lua/widget/widget.c b/src/lua/widget/widget.c
index f0fbe7abbdf8..d8194ac9417d 100644
--- a/src/lua/widget/widget.c
+++ b/src/lua/widget/widget.c
@@ -107,7 +107,7 @@ static int get_widget_params(lua_State *L)
   lua_pushnil(L); /* first key */
   while(lua_next(L, -2) != 0)
   {
-    g_signal_connect(widget->widget, lua_tostring(L,-2), G_CALLBACK(lua_touserdata(L,-1)), widget);
+    g_signal_connect_data(widget->widget, lua_tostring(L,-2), G_CALLBACK(lua_touserdata(L,-1)), widget, NULL, 0);
     lua_pop(L,1);
   }
   lua_pop(L,1);
diff --git a/src/osx/osx.mm b/src/osx/osx.mm
index 7b7132c7bb81..1a3276128978 100644
--- a/src/osx/osx.mm
+++ b/src/osx/osx.mm
@@ -86,7 +86,7 @@ void dt_osx_disallow_fullscreen(GtkWidget *widget)
   if(gtk_widget_get_realized(widget))
     dt_osx_disable_fullscreen(widget);
   else
-    g_signal_connect(G_OBJECT(widget), "realize", G_CALLBACK(dt_osx_disable_fullscreen), NULL);
+    g_signal_connect(widget, "realize", G_CALLBACK(dt_osx_disable_fullscreen), NULL);
 #endif
 #endif
 }
diff --git a/src/views/darkroom.c b/src/views/darkroom.c
index f96f077bca2b..a53fc51811eb 100644
--- a/src/views/darkroom.c
+++ b/src/views/darkroom.c
@@ -2456,7 +2456,7 @@ void gui_init(dt_view_t *self)
   dt_action_define(sa, NULL, N_("quick access to presets"),
                    favorite_presets, &dt_action_def_button);
   gtk_widget_set_tooltip_text(favorite_presets, _("quick access to presets"));
-  g_signal_connect(G_OBJECT(favorite_presets), "clicked",
+  g_signal_connect(favorite_presets, "clicked",
                    G_CALLBACK(_darkroom_ui_favorite_presets_popupmenu),
                    NULL);
   dt_gui_add_help_link(favorite_presets, "favorite_presets");
@@ -2466,7 +2466,7 @@ void gui_init(dt_view_t *self)
   /* create quick styles popup menu tool */
   GtkWidget *styles = dtgtk_button_new(dtgtk_cairo_paint_styles, 0, NULL);
   dt_action_define(sa, NULL, N_("quick access to styles"), styles, &dt_action_def_button);
-  g_signal_connect(G_OBJECT(styles), "clicked",
+  g_signal_connect(styles, "clicked",
                    G_CALLBACK(_darkroom_ui_apply_style_popupmenu), NULL);
   gtk_widget_set_tooltip_text(styles, _("quick access for applying any of your styles"));
   dt_gui_add_help_link(styles, "bottom_panel_styles");
@@ -2477,7 +2477,7 @@ void gui_init(dt_view_t *self)
   dev->second_wnd_button = dtgtk_togglebutton_new(dtgtk_cairo_paint_display2, 0, NULL);
   dt_action_define(sa, NULL, N_("second window"),
                    dev->second_wnd_button, &dt_action_def_toggle);
-  g_signal_connect(G_OBJECT(dev->second_wnd_button), "clicked",
+  g_signal_connect(dev->second_wnd_button, "clicked",
                    G_CALLBACK(_second_window_quickbutton_clicked),dev);
   gtk_widget_set_tooltip_text(dev->second_wnd_button,
                               _("display a second darkroom image window"));
@@ -2492,7 +2492,7 @@ void gui_init(dt_view_t *self)
                           &dt_action_def_toggle);
     gtk_widget_set_tooltip_text(dev->color_assessment.button, _("toggle color assessment conditions\nright-click for options"));
     dt_shortcut_register(ac, 0, 0, GDK_KEY_b, GDK_CONTROL_MASK);
-    g_signal_connect(G_OBJECT(dev->color_assessment.button), "toggled",
+    g_signal_connect(dev->color_assessment.button, "toggled",
                      G_CALLBACK(_full_color_assessment_callback), dev);
 
     dt_view_manager_module_toolbox_add(darktable.view_manager, dev->color_assessment.button, DT_VIEW_DARKROOM);
@@ -2511,7 +2511,7 @@ void gui_init(dt_view_t *self)
     gtk_widget_set_tooltip_text(border_width_slider,
                                 _("total border width in relation to the screen size for the assessment mode.\n"
                                   "this includes the outer gray part plus the inner white frame."));
-    g_signal_connect(G_OBJECT(border_width_slider), "value-changed",
+    g_signal_connect(border_width_slider, "value-changed",
                      G_CALLBACK(_color_assessment_border_width_callback), dev);
     gtk_box_pack_start(GTK_BOX(vbox), GTK_WIDGET(border_width_slider), TRUE, TRUE, 0);
 
@@ -2523,7 +2523,7 @@ void gui_init(dt_view_t *self)
     dt_bauhaus_widget_set_label(border_ratio_slider, N_("color_assessment"), N_("white border ratio"));
     gtk_widget_set_tooltip_text(border_ratio_slider,
                                 _("the border ratio specifies the fraction of the white part of the border."));
-    g_signal_connect(G_OBJECT(border_ratio_slider), "value-changed",
+    g_signal_connect(border_ratio_slider, "value-changed",
                      G_CALLBACK(_color_assessment_border_white_ratio_callback), dev);
     gtk_box_pack_start(GTK_BOX(vbox), GTK_WIDGET(border_ratio_slider), TRUE, TRUE, 0);
 
@@ -2539,7 +2539,7 @@ void gui_init(dt_view_t *self)
     (dev->late_scaling.button,
      _("toggle high quality processing."
        " if activated darktable processes image data as it does while exporting"));
-  g_signal_connect(G_OBJECT(dev->late_scaling.button), "clicked",
+  g_signal_connect(dev->late_scaling.button, "clicked",
                    G_CALLBACK(_latescaling_quickbutton_clicked), dev);
   dt_view_manager_module_toolbox_add(darktable.view_manager,
                                      dev->late_scaling.button, DT_VIEW_DARKROOM);
@@ -2557,7 +2557,7 @@ void gui_init(dt_view_t *self)
     dt_shortcut_register(ac, 0, 0, GDK_KEY_o, GDK_SHIFT_MASK);
     gtk_widget_set_tooltip_text(dev->rawoverexposed.button,
                                 _("toggle indication of raw overexposure\nright-click for options"));
-    g_signal_connect(G_OBJECT(dev->rawoverexposed.button), "clicked",
+    g_signal_connect(dev->rawoverexposed.button, "clicked",
                      G_CALLBACK(_rawoverexposed_quickbutton_clicked), dev);
     dt_view_manager_module_toolbox_add(darktable.view_manager,
                                        dev->rawoverexposed.button, DT_VIEW_DARKROOM);
@@ -2605,7 +2605,7 @@ void gui_init(dt_view_t *self)
                                 N_("clipping threshold"));
     gtk_widget_set_tooltip_text(
         threshold, _("threshold of what shall be considered overexposed\n1.0 - white level\n0.0 - black level"));
-    g_signal_connect(G_OBJECT(threshold), "value-changed",
+    g_signal_connect(threshold, "value-changed",
                      G_CALLBACK(_rawoverexposed_threshold_callback), dev);
     gtk_box_pack_start(GTK_BOX(vbox), GTK_WIDGET(threshold), TRUE, TRUE, 0);
 
@@ -2624,7 +2624,7 @@ void gui_init(dt_view_t *self)
     dt_shortcut_register(ac, 0, 0, GDK_KEY_o, 0);
     gtk_widget_set_tooltip_text(dev->overexposed.button,
                                 _("toggle clipping indication\nright-click for options"));
-    g_signal_connect(G_OBJECT(dev->overexposed.button), "clicked",
+    g_signal_connect(dev->overexposed.button, "clicked",
                      G_CALLBACK(_overexposed_quickbutton_clicked), dev);
     dt_view_manager_module_toolbox_add(darktable.view_manager,
                                        dev->overexposed.button, DT_VIEW_DARKROOM);
@@ -2680,7 +2680,7 @@ void gui_init(dt_view_t *self)
                                          "typical color glossy prints produce black at -8.00 EV,\n"
                                          "typical B&W glossy prints produce black at -9.00 EV."
                                          ));
-    g_signal_connect(G_OBJECT(lower), "value-changed",
+    g_signal_connect(lower, "value-changed",
                      G_CALLBACK(_lower_callback), dev);
     gtk_box_pack_start(GTK_BOX(vbox), GTK_WIDGET(lower), TRUE, TRUE, 0);
 
@@ -2692,7 +2692,7 @@ void gui_init(dt_view_t *self)
     /* xgettext:no-c-format */
     gtk_widget_set_tooltip_text(upper, _("clipping threshold for the white point.\n"
                                          "100% is peak medium luminance."));
-    g_signal_connect(G_OBJECT(upper), "value-changed", G_CALLBACK(_upper_callback), dev);
+    g_signal_connect(upper, "value-changed", G_CALLBACK(_upper_callback), dev);
     gtk_box_pack_start(GTK_BOX(vbox), GTK_WIDGET(upper), TRUE, TRUE, 0);
 
     gtk_widget_show_all(vbox);
@@ -2707,7 +2707,7 @@ void gui_init(dt_view_t *self)
     dt_shortcut_register(ac, 0, 0, GDK_KEY_s, GDK_CONTROL_MASK);
     gtk_widget_set_tooltip_text(dev->profile.softproof_button,
                                 _("toggle softproofing\nright-click for profile options"));
-    g_signal_connect(G_OBJECT(dev->profile.softproof_button), "clicked",
+    g_signal_connect(dev->profile.softproof_button, "clicked",
                      G_CALLBACK(_softproof_quickbutton_clicked), dev);
     dt_view_manager_module_toolbox_add(darktable.view_manager,
                                        dev->profile.softproof_button, DT_VIEW_DARKROOM);
@@ -2720,7 +2720,7 @@ void gui_init(dt_view_t *self)
     dt_shortcut_register(ac, 0, 0, GDK_KEY_g, GDK_CONTROL_MASK);
     gtk_widget_set_tooltip_text(dev->profile.gamut_button,
                  _("toggle gamut checking\nright-click for profile options"));
-    g_signal_connect(G_OBJECT(dev->profile.gamut_button), "clicked",
+    g_signal_connect(dev->profile.gamut_button, "clicked",
                      G_CALLBACK(_gamut_quickbutton_clicked), dev);
     dt_view_manager_module_toolbox_add(darktable.view_manager,
                                        dev->profile.gamut_button, DT_VIEW_DARKROOM);
@@ -2854,15 +2854,15 @@ void gui_init(dt_view_t *self)
     gtk_widget_set_tooltip_markup(histogram_profile, tooltip);
     g_free(tooltip);
 
-    g_signal_connect(G_OBJECT(display_profile), "value-changed",
+    g_signal_connect(display_profile, "value-changed",
                      G_CALLBACK(_display_profile_callback), dev);
-    g_signal_connect(G_OBJECT(display2_profile), "value-changed",
+    g_signal_connect(display2_profile, "value-changed",
                      G_CALLBACK(_display2_profile_callback), dev);
-    g_signal_connect(G_OBJECT(display2_color_assessment), "toggled",
+    g_signal_connect(display2_color_assessment, "toggled",
                      G_CALLBACK(_display2_color_assessment_callback), dev);
-    g_signal_connect(G_OBJECT(softproof_profile), "value-changed",
+    g_signal_connect(softproof_profile, "value-changed",
                      G_CALLBACK(_softproof_profile_callback), dev);
-    g_signal_connect(G_OBJECT(histogram_profile), "value-changed",
+    g_signal_connect(histogram_profile, "value-changed",
                      G_CALLBACK(_histogram_profile_callback), dev);
 
     _update_softproof_gamut_checking(dev);
@@ -2903,7 +2903,7 @@ void gui_init(dt_view_t *self)
     darktable.view_manager->guides_popover =
       dt_guides_popover(self, darktable.view_manager->guides_toggle);
     g_object_ref(darktable.view_manager->guides_popover);
-    g_signal_connect(G_OBJECT(darktable.view_manager->guides_toggle), "clicked",
+    g_signal_connect(darktable.view_manager->guides_toggle, "clicked",
                      G_CALLBACK(_guides_quickbutton_clicked), dev);
     connect_button_press_release(darktable.view_manager->guides_toggle,
                                  darktable.view_manager->guides_popover);
@@ -4016,24 +4016,24 @@ static void _darkroom_display_second_window(dt_develop_t *dev)
                           | darktable.gui->scroll_mask);
 
     /* connect callbacks */
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "draw",
+    g_signal_connect(dev->preview2.widget, "draw",
                      G_CALLBACK(_second_window_draw_callback), dev);
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "scroll-event",
+    g_signal_connect(dev->preview2.widget, "scroll-event",
                      G_CALLBACK(_second_window_scrolled_callback), dev);
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "button-press-event",
+    g_signal_connect(dev->preview2.widget, "button-press-event",
                      G_CALLBACK(_second_window_button_pressed_callback), dev);
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "button-release-event",
+    g_signal_connect(dev->preview2.widget, "button-release-event",
                      G_CALLBACK(_second_window_button_released_callback), dev);
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "motion-notify-event",
+    g_signal_connect(dev->preview2.widget, "motion-notify-event",
                      G_CALLBACK(_second_window_mouse_moved_callback), dev);
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "leave-notify-event",
+    g_signal_connect(dev->preview2.widget, "leave-notify-event",
                      G_CALLBACK(_second_window_leave_callback), dev);
-    g_signal_connect(G_OBJECT(dev->preview2.widget), "configure-event",
+    g_signal_connect(dev->preview2.widget, "configure-event",
                      G_CALLBACK(_second_window_configure_callback), dev);
 
-    g_signal_connect(G_OBJECT(dev->second_wnd), "delete-event",
+    g_signal_connect(dev->second_wnd, "delete-event",
                      G_CALLBACK(_second_window_delete_callback), dev);
-    g_signal_connect(G_OBJECT(dev->second_wnd), "event",
+    g_signal_connect(dev->second_wnd, "event",
                      G_CALLBACK(dt_shortcut_dispatcher), NULL);
 
     _darkroom_ui_second_window_init(dev->second_wnd, dev);
diff --git a/src/views/lighttable.c b/src/views/lighttable.c
index 0d8e7bb990a9..4f39913887ad 100644
--- a/src/views/lighttable.c
+++ b/src/views/lighttable.c
@@ -1243,7 +1243,7 @@ void gui_init(dt_view_t *self)
   lib->profile_floating_window = gtk_popover_new(profile_button);
 
   g_object_set(G_OBJECT(lib->profile_floating_window), "transitions-enabled", FALSE, NULL);
-  g_signal_connect_swapped(G_OBJECT(profile_button), "button-press-event",
+  g_signal_connect_swapped(profile_button, "button-press-event",
                            G_CALLBACK(gtk_widget_show_all), lib->profile_floating_window);
 
   GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
@@ -1310,9 +1310,9 @@ void gui_init(dt_view_t *self)
   gtk_widget_set_tooltip_markup(display2_profile, tooltip);
   g_free(tooltip);
 
-  g_signal_connect(G_OBJECT(display_profile), "value-changed", G_CALLBACK(_profile_display_profile_callback), NULL);
+  g_signal_connect(display_profile, "value-changed", G_CALLBACK(_profile_display_profile_callback), NULL);
 
-  g_signal_connect(G_OBJECT(display2_profile), "value-changed", G_CALLBACK(_profile_display2_profile_callback),
+  g_signal_connect(display2_profile, "value-changed", G_CALLBACK(_profile_display2_profile_callback),
                    NULL);
 
   // update the gui when profiles change
diff --git a/src/views/map.c b/src/views/map.c
index 497bfb3ce24d..a02d33e290aa 100644
--- a/src/views/map.c
+++ b/src/views/map.c
@@ -777,14 +777,14 @@ void init(dt_view_t *self)
 
     g_signal_connect(GTK_WIDGET(lib->map), "changed",
                      G_CALLBACK(_view_map_changed_callback), self);
-    g_signal_connect_after(G_OBJECT(lib->map), "button-press-event",
+    g_signal_connect_after(lib->map, "button-press-event",
                            G_CALLBACK(_view_map_button_press_callback), self);
-    g_signal_connect_after(G_OBJECT(lib->map), "button-release-event",
+    g_signal_connect_after(lib->map, "button-release-event",
                           G_CALLBACK(_view_map_button_release_callback), self);
-    g_signal_connect(G_OBJECT(lib->map), "motion-notify-event",
+    g_signal_connect(lib->map, "motion-notify-event",
                      G_CALLBACK(_view_map_motion_notify_callback),
                      self);
-    g_signal_connect(G_OBJECT(lib->map), "drag-motion",
+    g_signal_connect(lib->map, "drag-motion",
                      G_CALLBACK(_view_map_drag_motion_callback),
                      self);
   }
diff --git a/src/views/view.c b/src/views/view.c
index bebc33493f90..7b8d60653fb2 100644
--- a/src/views/view.c
+++ b/src/views/view.c
@@ -1501,7 +1501,7 @@ void dt_view_accels_show(dt_view_manager_t *vm)
   vm->accels_window.sticky_btn = dtgtk_button_new(dtgtk_cairo_paint_multiinstance, 0, NULL);
   gtk_widget_set_tooltip_text(vm->accels_window.sticky_btn,
                               _("switch to a classic window which will stay open after key release"));
-  g_signal_connect(G_OBJECT(vm->accels_window.sticky_btn), "button-press-event",
+  g_signal_connect(vm->accels_window.sticky_btn, "button-press-event",
                    G_CALLBACK(_accels_window_sticky),
                    vm);
   dt_gui_add_class(vm->accels_window.sticky_btn, "dt_accels_stick");
diff --git a/tools/generate_prefs.xsl b/tools/generate_prefs.xsl
index 58cf1b30f523..73225385dfa6 100644
--- a/tools/generate_prefs.xsl
+++ b/tools/generate_prefs.xsl
@@ -188,7 +188,7 @@ static void wrapup_pref(const gchar *name,
   gtk_grid_attach(GTK_GRID(grid), labdef, 1, *line, 1, 1);
   gtk_grid_attach(GTK_GRID(grid), widget, 2, (*line)++, 1, 1);
   gtk_label_set_mnemonic_widget(GTK_LABEL(label), widget);
-  g_signal_connect(G_OBJECT(labelev), "button-press-event", G_CALLBACK(callback), (gpointer)widget);
+  g_signal_connect(labelev, "button-press-event", G_CALLBACK(callback), widget);
 }
 
 static gboolean click_widget_label(GtkWidget *label, GdkEventButton *event, GtkWidget *widget)
@@ -302,14 +302,14 @@ gboolean restart_required = FALSE;
   <!-- restart callbacks (on change) -->
 
   <xsl:for-each select="./dtconfiglist/dtconfig[@prefs or @dialog]">
-    <xsl:text>static void&#xA;preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text> (GtkWidget *widget, gpointer user_data)&#xA;{&#xA;</xsl:text>
+    <xsl:text>static void&#xA;preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text> (GtkWidget *widget, GtkWidget *label)&#xA;{&#xA;</xsl:text>
     <xsl:if test="@restart">
       <xsl:text>  restart_required = TRUE;&#xA;</xsl:text>
     </xsl:if>
     <xsl:apply-templates select="type" mode="factor"/>
     <xsl:text>
   set_widget_label_default(widget, "</xsl:text>
-    <xsl:value-of select="name"/><xsl:text>", GTK_WIDGET(user_data), factor);</xsl:text>
+    <xsl:value-of select="name"/><xsl:text>", label, factor);</xsl:text>
     <xsl:text>&#xA;}&#xA;&#xA;</xsl:text>
   </xsl:for-each>
 
@@ -561,8 +561,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     gchar *setting = dt_conf_get_string("</xsl:text><xsl:value-of select="name"/><xsl:text>");
     gtk_text_buffer_set_text(buffer, setting, strlen(setting));
     g_free(setting);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
-    g_signal_connect(G_OBJECT(widget), "key-press-event", G_CALLBACK(handle_enter_key), NULL);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "key-press-event", G_CALLBACK(handle_enter_key), NULL);
     snprintf(tooltip, 1024, _("double click to reset to `%s'"), "</xsl:text><xsl:value-of select="default"/><xsl:text>");
     gtk_widget_set_tooltip_text(labelev, tooltip);</xsl:text>
   </xsl:template>
@@ -575,8 +575,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     gtk_entry_set_text(GTK_ENTRY(widget), setting);
     g_free(setting);
     gtk_label_set_mnemonic_widget(GTK_LABEL(label), widget);
-    g_signal_connect(G_OBJECT(widget), "changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     snprintf(tooltip, 1024, _("double click to reset to `%s'"), "</xsl:text><xsl:value-of select="default"/><xsl:text>");
     gtk_widget_set_tooltip_text(labelev,  tooltip);</xsl:text>
   </xsl:template>
@@ -590,8 +590,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     gchar *setting = dt_conf_get_string("</xsl:text><xsl:value-of select="name"/><xsl:text>");
     gtk_file_chooser_set_current_folder(GTK_FILE_CHOOSER(widget), setting);
     g_free(setting);
-    g_signal_connect(G_OBJECT(widget), "selection-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "selection-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     gchar *default_path = dt_conf_expand_default_dir("</xsl:text><xsl:value-of select="default"/><xsl:text>");
     snprintf(tooltip, 1024, _("double click to reset to `%s'"), default_path);
     g_free(default_path);
@@ -613,8 +613,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     gtk_size_group_add_widget(widget_group, widget);
     gtk_spin_button_set_digits(GTK_SPIN_BUTTON(widget), 0);
     gtk_spin_button_set_value(GTK_SPIN_BUTTON(widget), dt_conf_get_int("</xsl:text><xsl:value-of select="name"/><xsl:text>") * factor);
-    g_signal_connect(G_OBJECT(widget), "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     snprintf(tooltip, 1024, _("double click to reset to `%d'"), (int)(</xsl:text><xsl:value-of select="default"/><xsl:text> * factor));
     gtk_widget_set_tooltip_text(labelev, tooltip);</xsl:text>
   </xsl:template>
@@ -632,8 +632,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     gtk_size_group_add_widget(widget_group, widget);
     gtk_spin_button_set_digits(GTK_SPIN_BUTTON(widget), 0);
     gtk_spin_button_set_value(GTK_SPIN_BUTTON(widget), dt_conf_get_int64("</xsl:text><xsl:value-of select="name"/><xsl:text>") * factor);
-    g_signal_connect(G_OBJECT(widget), "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     char value[100];
     snprintf(value, 100, "%"G_GINT64_FORMAT"",(gint64)(</xsl:text><xsl:value-of select="default"/><xsl:text> * factor));
     snprintf(tooltip, 1024, _("double click to reset to `%s'"), value);
@@ -651,8 +651,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     widget = gtk_spin_button_new_with_range(min, max, 0.001f);
     gtk_spin_button_set_digits(GTK_SPIN_BUTTON(widget), 5);
     gtk_spin_button_set_value(GTK_SPIN_BUTTON(widget), dt_conf_get_float("</xsl:text><xsl:value-of select="name"/><xsl:text>") * factor);
-    g_signal_connect(G_OBJECT(widget), "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     snprintf(tooltip, 1024, _("double click to reset to `%.03f'"), </xsl:text><xsl:value-of select="default"/><xsl:text> * factor);
     gtk_widget_set_tooltip_text(labelev, tooltip);</xsl:text>
   </xsl:template>
@@ -661,8 +661,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     <xsl:text>
     widget = gtk_check_button_new();
     gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(widget), dt_conf_get_bool("</xsl:text><xsl:value-of select="name"/><xsl:text>"));
-    g_signal_connect(G_OBJECT(widget), "toggled", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "toggled", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     snprintf(tooltip, 1024, _("double click to reset to `%s'"), C_("preferences", "</xsl:text><xsl:value-of select="translate(default, $lowercase, $uppercase)"/><xsl:text>"));
     gtk_widget_set_tooltip_text(labelev, tooltip);</xsl:text>
   </xsl:template>
@@ -681,8 +681,8 @@ static void init_tab_generated(GtkWidget *dialog, GtkWidget *stack)
     <xsl:text>
     gtk_widget_set_halign(widget, GTK_ALIGN_START);
     gtk_size_group_add_widget(widget_group, widget);
-    g_signal_connect(G_OBJECT(widget), "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
-    g_signal_connect(G_OBJECT(dialog), "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
+    g_signal_connect(widget, "value-changed", G_CALLBACK(preferences_changed_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), labdef);
+    g_signal_connect(dialog, "response", G_CALLBACK(preferences_response_callback_</xsl:text><xsl:value-of select="generate-id(.)"/><xsl:text>), widget);
     snprintf(tooltip, 1024, _("double click to reset to `%s'"), C_("preferences", "</xsl:text><xsl:value-of select="default"/><xsl:text>"));
     gtk_widget_set_tooltip_text(labelev, tooltip);</xsl:text>
   </xsl:template>