Fix MenuListener not fired for menubar DROP_DOWN menus on GTK4

[Copilot]

On GTK4, MenuListener.menuShown/menuHidden are never fired for SWT.DROP_DOWN menus attached to a menubar — only popup menus (SWT.POP_UP) work.

Root Cause

In GTK4, SWT.DROP_DOWN menus use a GMenuModel as their handle (not a real GTK widget), so SHOW/HIDE signals cannot be connected to them directly. The visible popover widgets are created internally by GtkPopoverMenuBar as private GtkPopoverMenuBarItem children, each owning a GtkPopoverMenu. SWT had no visibility into these internal widgets.

Changes

• Menu.java
  • Add popoverHandle field on DROP_DOWN menus to track the GTK-internal GtkPopoverMenu
  • Connect the MAP signal to BAR menus in hookEvents() — the bar's GtkPopoverMenuBarItem children exist by the time the bar maps
  • Override gtk_map(): when the bar maps, call connectDropDownMenuSignals() to wire up signal routing for all submenus
  • connectDropDownMenuSignals(): iterates GtkPopoverMenuBarItem children in lockstep with items, finds each item's GtkPopoverMenu by type name, registers it in SWT's widget table (keyed to the DROP_DOWN Menu), and connects SHOW/HIDE signals — these route through the existing gtk_show()/gtk_hide() handlers which fire SWT.Show/SWT.Hide
  • findGtkPopoverMenuChild(): walks a GtkPopoverMenuBarItem's direct children looking for type name "GtkPopoverMenu"
  • Override deregister() on DROP_DOWN menus to remove the popover from the widget table on dispose, preventing stale signal dispatch

Menu fileMenu = new Menu(shell, SWT.DROP_DOWN);
fileItem.setMenu(fileMenu);

fileMenu.addMenuListener(new MenuListener() {
    @Override public void menuShown(MenuEvent e)  { /* now fires on GTK4 */ }
    @Override public void menuHidden(MenuEvent e) { /* now fires on GTK4 */ }
});

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• repo.eclipse.org
  • Triggering command: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java --enable-native-access=ALL-UNNAMED -classpath /opt/hostedtoolcache/maven/3.9.12/x64/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/opt/hostedtoolcache/maven/3.9.12/x64/bin/m2.conf -Dmaven.home=/opt/hostedtoolcache/maven/3.9.12/x64 -Dlibrary.jansi.path=/opt/hostedtoolcache/maven/3.9.12/x64/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/eclipse.platform.swt/eclipse.platform.swt org.codehaus.plexus.classworlds.launcher.Launcher compile -pl bundles/org.eclipse.swt -Dnative=gtk.linux.x86_64 -q -l as -lcairo rin-Hotspot_jdk/--norc rin-Hotspot_jdk/--noprofile b-2.0 (dns block)
  • Triggering command: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java --enable-native-access=ALL-UNNAMED -classpath /opt/hostedtoolcache/maven/3.9.12/x64/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/opt/hostedtoolcache/maven/3.9.12/x64/bin/m2.conf -Dmaven.home=/opt/hostedtoolcache/maven/3.9.12/x64 -Dlibrary.jansi.path=/opt/hostedtoolcache/maven/3.9.12/x64/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/eclipse.platform.swt/eclipse.platform.swt org.codehaus.plexus.classworlds.launcher.Launcher compile -pl bundles/org.eclipse.swt -Dnative=gtk.linux.x86_64 ableScrollsPastContent.java adioButtonNotRendered.java nu_setVisible.java sesHeader.java fbuzz (dns block)
  • Triggering command: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java --enable-native-access=ALL-UNNAMED -classpath /opt/hostedtoolcache/maven/3.9.12/x64/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/opt/hostedtoolcache/maven/3.9.12/x64/bin/m2.conf -Dmaven.home=/opt/hostedtoolcache/maven/3.9.12/x64 -Dlibrary.jansi.path=/opt/hostedtoolcache/maven/3.9.12/x64/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/eclipse.platform.swt/eclipse.platform.swt org.codehaus.plexus.classworlds.launcher.Launcher test -pl tests/org.eclipse.swt.tests -Dtest=Test_org_eclipse_swt_widgets_Menu -q origin n-Hotspot_jdk/21.0.10-7/x64/include/linux (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>MenuListener on GTK4 not called</issue_title>
<issue_description>If a menu listener is added to menu in menubar , menu listener is not called. It works for a popup menu though.
Snippet to test is:

import org.eclipse.swt.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.widgets.*;

public class MenuListenerTest {
    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("MenuListener Test");

        Menu menuBar = new Menu(shell, SWT.BAR);
        shell.setMenuBar(menuBar);

        MenuItem fileItem = new MenuItem(menuBar, SWT.CASCADE);
        fileItem.setText("File");

        Menu fileMenu = new Menu(shell, SWT.DROP_DOWN);
        fileItem.setMenu(fileMenu);

        fileMenu.addMenuListener(new MenuListener() {
            @Override
            public void menuShown(MenuEvent e) {
                System.out.println("Menu shown");
            }

            @Override
            public void menuHidden(MenuEvent e) {
                System.out.println("Menu hidden");
            }
        });

        new MenuItem(fileMenu, SWT.PUSH).setText("Item 1");

        shell.setSize(200, 150);
        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) display.sleep();
        }
        display.dispose();
    }
}

```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes MenuListener on GTK4 not called #101

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.