Allow adding multiple jars at once

src/matcher/gui/Gui.java

@@ -12,6 +12,7 @@
 import java.util.concurrent.Executors;
 import java.util.function.Consumer;
 import java.util.function.DoubleConsumer;
+import java.util.stream.Collectors;
 
 import javafx.application.Application;
 import javafx.application.Platform;
@@ -306,6 +307,20 @@ public static Path requestFile(String title, Window parent, List<ExtensionFilter
 		return file.toPath();
 	}
 
+    public static List<Path> requestFiles(String title, Window parent, List<ExtensionFilter> extensionFilters) {
+        FileChooser fileChooser = new FileChooser();
+
+        fileChooser.setTitle(title);
+        fileChooser.getExtensionFilters().addAll(extensionFilters);
+        if (lastChooserFile != null) fileChooser.setInitialDirectory(lastChooserFile);
+
+        List<File> files = fileChooser.showOpenMultipleDialog(parent);
+
+        if (!files.isEmpty()) lastChooserFile = files.get(0).getParentFile();
+
+        return files.stream().map(File::toPath).collect(Collectors.toList());
+    }
+
 	public static Path requestDir(String title, Window parent) {
 		DirectoryChooser fileChooser = new DirectoryChooser();
 

src/matcher/gui/menu/NewProjectPane.java

@@ -176,10 +176,12 @@ private Node createFilesSelectionPane(String name, ObservableList<Path> entries,
 
 		Button button = new Button("add");
 		footer.getChildren().add(button);
-		button.setOnAction(event -> {
-			Path path = Gui.requestFile("Select file to add", window, getInputLoadExtensionFilters(), true);
-			if (path != null && !list.getItems().contains(path)) list.getItems().add(path);
-		});
+		button.setOnAction(event ->
+				Gui.requestFiles("Select files to add", window, getInputLoadExtensionFilters())
+				   .stream()
+				   .filter(path -> !list.getItems().contains(path))
+				   .forEach(path -> list.getItems().add(path))
+		);
 
 		Button removeButton = new Button("remove");
 		footer.getChildren().add(removeButton);