Initial libadwaita support for GTK4 backend #3925

johnzhou721 · 2025-11-27T04:03:33Z

Adds initial support for Window, Application, and ActivityIndicator for libadwaita. This PR thus makes all currently implemented GTK4 functionalities compatible with libadwaita.

Corners are now rounded -- yay!!!

PR Checklist:

All new features have been tested
All new features have been documented
I have read the CONTRIBUTING.md file
I will abide by the code of conduct

johnzhou721

Some comments inline about the way things are in this PR.

This PR makes all currently implemented GTK4 functionalities compatible with libadwaita, which is why ActivityIndicator is in here.

Ready for review.

johnzhou721 · 2025-11-28T02:00:11Z

testbed/tests/testbed.py

+            "cover-if-plain-gtk4": "os_environ.get('TOGA_GTK', '') != '4' or "
+            "os_environ.get('TOGA_GTKLIB', '') != ''",
+            "cover-if-plain-gtk": "os_environ.get('TOGA_GTKLIB', '') != ''",
+            "cover-if-libadwaita": "os_environ.get('TOGA_GTK', '') != '4' or "
+            "os_environ.get('TOGA_GTKLIB', '') != 'Adw'",


Is following the no-cover prefix convention perhaps better here? I thought it'd be better to be like "cover [only] if plain gtk" rather than the contrapositive "no cover if not plain gtk".

The "no cover" prefix has historical precedence in testing, but the "if" part doesn't have to be preserved - so no-cover-unless-adwaita would be viable

johnzhou721 · 2025-11-28T02:01:02Z

gtk/tests_backend/app.py

+        if Adw is None:
+            assert isinstance(self.app._impl.native, Gtk.Application)
+        else:
+            assert isinstance(self.app._impl.native, Adw.Application)


Technically, Adw.Application subclasses Gtk.Application... however, I used this stronger assertion because without Adw.Application, window bottom corners doesn't round at all.

Same with Adw.Window

johnzhou721 · 2025-11-28T02:01:45Z

gtk/src/toga_gtk/widgets/activityindicator.py

+    # libadwaita 1.6.0 is not in Ubuntu 24.04 yet; no-cover it.
+    if Adw is not None and ADW_VERSION >= (1, 6, 0):  # pragma: no cover


Does this no-cover perhaps makes you nervous? Should we land Adwaita 1.6.0 changes until all majors distros ship it? Right now Ubuntu 24.04 does not.

On the basis that this means we're not actually testing half the implementation - yes, this does make me nervous.

I'd need more context to make a call on how to handle this though. What's the motivation for setting a 1.6 minimum? What distributions do provide 1.6?

@freakboy3742 Adw.Spinner was added in libadwaita 1.6 only.

Debian 13 has libadwaita 1.8, even Fedora 41 has libadwaita 1.6.0, Arch has 1.8.2, OpenSUSE Tumbleweed has 1.8.2.

It seems that Ubuntu 24.04 is the only one that does not provide libadwaita 1.6.

Ubuntu 24.04 also doesn't provide python3-pyside6.MODULE pcakages... I wonder what the heck happened with it. I just can't wait until next August...

johnzhou721 · 2025-11-28T02:01:57Z

gtk/src/toga_gtk/libs/gtk.py

 GLIB_VERSION: tuple[int, int, int] = (
    GLib.MAJOR_VERSION,
-    GLib.MAJOR_VERSION,
-    GLib.MAJOR_VERSION,
+    GLib.MINOR_VERSION,
+    GLib.MICRO_VERSION,
 )


I can't believe I didn't catch this before...

johnzhou721 · 2025-11-28T02:02:44Z

.github/workflows/ci.yml

+        - "linux-wayland-gtk4-adw"
+        - "linux-wayland-qt"
+        - "linux-x11-qt"


FYI -- the Qt things worked before because Qt overrode all the variables in the include section.

johnzhou721 · 2025-11-28T02:13:31Z

docs/en/reference/platforms/linux/gtk.md

 $ export TOGA_GTK=4
 ```

+The experimental GTK 4 backend also aims to provides support for integrating with desktop environment-specific libraries.  At present, `libadwaita` is the only supported library of this kind.  This functionality requires libadwaita 1.5 or newer.  To enable libadwaita integration support, set:


libadwaita 1.5 changed the way dialog things are handled, and also the application "about" dialogs. The relevant APIs are deprecated in libadwaita 1.6.

All major distros ship libadwaita 1.5+. Most major distros ship libadwaita 1.6+.

Is there a reason to make libadwaita support optional/opt in? Based on your previous descriptions, it's the sort of thing that, if available, should be Just Used - or, at the very least, opt-out.

@freakboy3742 But there's non-GNOME GTK distros. Should we say that they're minor enough to assume GNOME by default?

Or we could also check XDG_CURRENT_DESKTOP as a default. Which option would you prefer?

kattni · 2025-12-07T23:14:41Z

@johnzhou721 Can you verify whether this is ready for review? Thanks.

johnzhou721 · 2025-12-07T23:51:31Z

@kattni Verified. I explicitedly stated this and resolved the next comment about CI fails.

kattni · 2025-12-08T00:12:38Z

@johnzhou721 When something is ready for review, that means that there are no other changes necessary. When there are commits after you state that it is ready for review, the assumption will be that it is not, in fact, ready for review. Therefore, I will verify with you whether it is actually ready, before handing it off.

In the future, if you would like to avoid this, please ensure that you have all your intended changes completed before asking for a review, and if you do need to submit more changes, please restate that it is ready once you have completed those.

Remove the 'invalid_size_while_hidden' attribute from BoxProbe.

johnzhou721 · 2025-12-08T01:36:10Z

@kattni Thanks for letting me know about what caused the confusion. I'll try to avoid doing this in the future, but in this case it was neccesary.

For a specific explanation, the commit resolves an artifact from the merge; it was hard for me to test all the environments at once locally. However I understand that this is not an excuse — and I apologize for spending a bit of your time doing the verification.

Since then I realized an error in the commit you referenced -- I've pushed another update, and reconfirming this is ready for review.

kattni · 2025-12-08T01:45:20Z

@johnzhou721 Thank you for following up. I've handed this off to Russell.

To be clear, I'm not saying that you can't submit subsequent commits, I'm simply saying that you need to let us know afterwards that it is again ready for review.

freakboy3742

A few questions/comments about testing and the opt-in nature of the proposed behavior.

freakboy3742 · 2025-11-28T05:50:26Z

docs/en/reference/platforms/linux/gtk.md

 $ export TOGA_GTK=4
 ```

+The experimental GTK 4 backend also aims to provides support for integrating with desktop environment-specific libraries.  At present, `libadwaita` is the only supported library of this kind.  This functionality requires libadwaita 1.5 or newer.  To enable libadwaita integration support, set:


Is there a reason to make libadwaita support optional/opt in? Based on your previous descriptions, it's the sort of thing that, if available, should be Just Used - or, at the very least, opt-out.

docs/en/reference/platforms/linux/gtk.md

freakboy3742 · 2025-11-28T05:56:31Z

gtk/src/toga_gtk/widgets/activityindicator.py

+    # libadwaita 1.6.0 is not in Ubuntu 24.04 yet; no-cover it.
+    if Adw is not None and ADW_VERSION >= (1, 6, 0):  # pragma: no cover


On the basis that this means we're not actually testing half the implementation - yes, this does make me nervous.

I'd need more context to make a call on how to handle this though. What's the motivation for setting a 1.6 minimum? What distributions do provide 1.6?

freakboy3742 · 2025-12-12T04:31:15Z

testbed/tests/testbed.py

+            "cover-if-plain-gtk4": "os_environ.get('TOGA_GTK', '') != '4' or "
+            "os_environ.get('TOGA_GTKLIB', '') != ''",
+            "cover-if-plain-gtk": "os_environ.get('TOGA_GTKLIB', '') != ''",
+            "cover-if-libadwaita": "os_environ.get('TOGA_GTK', '') != '4' or "
+            "os_environ.get('TOGA_GTKLIB', '') != 'Adw'",


The "no cover" prefix has historical precedence in testing, but the "if" part doesn't have to be preserved - so no-cover-unless-adwaita would be viable

Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>

Added possessive forms for 'elementaryOS' and 'tauOS'.

johnzhou721 added 6 commits November 26, 2025 22:00

Initial libadwaita support.

19750dd

Add changenote

e3d49d3

Conditionally define ADW_VERSION based on Adw availability

17b21f5

Rehint by version

1586cda

Refactor Adw import logic for GTK version 4.0

994dc7b

Add additional Linux and Qt platforms to CI workflow

b4cd3a8

johnzhou721 marked this pull request as draft November 27, 2025 04:44

johnzhou721 and others added 8 commits November 27, 2025 13:49

fix coverage issues

b42ee97

Fix coverage rule

b797f46

Update environment variable conditions for GTK

e0a7069

Fix up tests on libadwaita >= 1.6

cc62359

Pre-commit fixes

4517f72

Document libadwaita support.

184d3ad

Add to spelling wordlist

5351fcc

Bump minimum versions.

7435bde

johnzhou721 commented Nov 28, 2025

View reviewed changes

johnzhou721 marked this pull request as ready for review November 28, 2025 02:14

johnzhou721 added 2 commits November 27, 2025 20:15

Merge branch 'beeware:main' into adw

8247559

Move probe flag

22aa62d

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johnzhou721 added 2 commits November 27, 2025 22:25

Merge branch 'beeware:main' into adw

2c79b13

Merge branch 'main' into adw

4c65a01

Remove extra probe flag

be5918f

Remove the 'invalid_size_while_hidden' attribute from BoxProbe.

kattni requested a review from freakboy3742 December 8, 2025 01:45

freakboy3742 requested changes Dec 12, 2025

View reviewed changes

johnzhou721 and others added 3 commits December 12, 2025 16:50

Update docs/en/reference/platforms/linux/gtk.md

5febd0a

Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>

Merge branch 'main' into adw

4b04b85

Add possessive forms for elementaryOS and tauOS

590a8c8

Added possessive forms for 'elementaryOS' and 'tauOS'.

		# libadwaita 1.6.0 is not in Ubuntu 24.04 yet; no-cover it.
		if Adw is not None and ADW_VERSION >= (1, 6, 0): # pragma: no cover

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Initial libadwaita support for GTK4 backend #3925

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Initial libadwaita support for GTK4 backend #3925

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kattni commented Dec 7, 2025

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johnzhou721 commented Nov 27, 2025 •

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