[Gtk4] Fix Show/Hide events of Menu in menu bar

Hook into "map" of the GtkPopoverMenu to make it register for show/hide
signals.

Author: akurtakov

bundles/org.eclipse.swt/Eclipse SWT PI/gtk/library/gtk4.c

@@ -26,6 +26,18 @@
   #pragma warning (disable: 4100)
 #endif
 
+#ifndef NO_GTK_1IS_1POPOVER_1MENU
+JNIEXPORT jboolean JNICALL GTK4_NATIVE(GTK_1IS_1POPOVER_1MENU)
+	(JNIEnv *env, jclass that, jlong arg0)
+{
+	jboolean rc = 0;
+	GTK4_NATIVE_ENTER(env, that, GTK_1IS_1POPOVER_1MENU_FUNC);
+	rc = (jboolean)GTK_IS_POPOVER_MENU(arg0);
+	GTK4_NATIVE_EXIT(env, that, GTK_1IS_1POPOVER_1MENU_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_gdk_1clipboard_1get_1content
 JNIEXPORT jlong JNICALL GTK4_NATIVE(gdk_1clipboard_1get_1content)
 	(JNIEnv *env, jclass that, jlong arg0)

bundles/org.eclipse.swt/Eclipse SWT PI/gtk/library/gtk4_stats.h

@@ -20,6 +20,7 @@
 #endif
 
 typedef enum {
+	GTK_1IS_1POPOVER_1MENU_FUNC,
 	gdk_1clipboard_1get_1content_FUNC,
 	gdk_1clipboard_1get_1formats_FUNC,
 	gdk_1clipboard_1is_1local_FUNC,

bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk4/GTK4.java

@@ -30,6 +30,8 @@ public class GTK4 {
 	public static final int GTK_PICK_INSENSITIVE = 1;
 	public static final int GTK_PICK_NON_TARGETABLE = 2;
 
+	public static final native boolean GTK_IS_POPOVER_MENU(long obj);
+
 	/**
 	 * @param context cast=(GtkIMContext *)
 	 * @param event cast=(GdkEvent *)

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Menu.java

@@ -55,7 +55,7 @@ public class Menu extends Widget {
 	long menuHandle;
 
 	/** GTK4 only fields */
-	long modelHandle, actionGroup, shortcutController;
+	long modelHandle, popoverHandle, actionGroup, shortcutController;
 
 	class Section {
 		LinkedList<MenuItem> sectionItems;
@@ -822,6 +822,50 @@ public boolean getVisible () {
 	return GTK.gtk_widget_get_mapped (handle);
 }
 
+@Override
+long gtk_map (long widget) {
+	if (GTK.GTK4 && (style & SWT.BAR) != 0) {
+		/*
+		 * The GtkPopoverMenuBar has been mapped, which means its internal
+		 * GtkPopoverMenuBarItem children now exist. Find the GtkPopoverMenu child for each,
+		 * and connect SHOW/HIDE signals so that SWT MenuListeners on DROP_DOWN are notified.
+		 */
+		connectDropDownMenuSignals();
+	}
+	return super.gtk_map(widget);
+}
+
+private void connectDropDownMenuSignals() {
+	if (items == null) return;
+	long barItem = GTK4.gtk_widget_get_first_child(handle);
+
+	for (MenuItem menuItem : items) {
+		if (barItem == 0) break;
+		if ((menuItem.style & SWT.SEPARATOR) != 0) continue;
+		if (menuItem.menu != null && menuItem.menu.popoverHandle == 0) {
+			long popover = findGtkPopoverMenuChild(barItem);
+			if (popover != 0) {
+				menuItem.menu.popoverHandle = popover;
+				display.addWidget(popover, menuItem.menu);
+				OS.g_signal_connect_closure_by_id(popover, display.signalIds[SHOW], 0, display.getClosure(SHOW), false);
+				OS.g_signal_connect_closure_by_id(popover, display.signalIds[HIDE], 0, display.getClosure(HIDE), false);
+			}
+		}
+		barItem = GTK4.gtk_widget_get_next_sibling(barItem);
+	}
+}
+
+private long findGtkPopoverMenuChild(long barItem) {
+	long child = GTK4.gtk_widget_get_first_child(barItem);
+	while (child != 0) {
+		if (GTK4.GTK_IS_POPOVER_MENU(child)) {
+			return child;
+		}
+		child = GTK4.gtk_widget_get_next_sibling(child);
+	}
+	return 0;
+}
+
 @Override
 long gtk_hide (long widget) {
 	if ((style & SWT.POP_UP) != 0) {
@@ -911,6 +955,15 @@ void hookEvents() {
 		if ((style & SWT.DROP_DOWN) == 0) {
 			OS.g_signal_connect_closure_by_id(handle, display.signalIds[SHOW], 0, display.getClosure(SHOW), false);
 			OS.g_signal_connect_closure_by_id(handle, display.signalIds[HIDE], 0, display.getClosure(HIDE), false);
+			if ((style & SWT.BAR) != 0) {
+				/*
+				 * Connect MAP signal on the GtkPopoverMenuBar so that once it is
+				 * realized and its internal GtkPopoverMenuBarItem children exist,
+				 * we can find the GtkPopoverMenu for each DROP_DOWN submenu and
+				 * route SHOW/HIDE signals back to the SWT DROP_DOWN Menu.
+				 */
+				OS.g_signal_connect_closure_by_id(handle, display.signalIds[MAP], 0, display.getClosure(MAP), false);
+			}
 		}
 
 	} else {
@@ -1044,6 +1097,15 @@ void destroyWidget () {
 	}
 }
 
+@Override
+void deregister() {
+	super.deregister();
+	if (GTK.GTK4 && (style & SWT.DROP_DOWN) != 0 && popoverHandle != 0) {
+		display.removeWidget(popoverHandle);
+		popoverHandle = 0;
+	}
+}
+
 /**
  * Removes the listener from the collection of listeners who will
  * be notified when the menu events are generated for the control.