WindowManager: Only show notifications after their window was shown (#2183)

Co-authored-by: Leonhard <[email protected]>

Author: lenemter

src/InternalUtils.vala

@@ -340,16 +340,22 @@ namespace Gala {
 
         public static void wait_for_window_actor (Meta.Window window, owned WindowActorReadyCallback callback) {
             unowned var window_actor = (Meta.WindowActor) window.get_compositor_private ();
-            if (window_actor != null) {
+            if (window_actor != null && window_actor.visible) {
                 callback (window_actor);
                 return;
             }
 
             Idle.add (() => {
                 window_actor = (Meta.WindowActor) window.get_compositor_private ();
 
-                if (window_actor != null) {
+                if (window_actor != null && window_actor.visible) {
                     callback (window_actor);
+                } else if (window_actor != null) {
+                    ulong show_handler = 0;
+                    show_handler = window_actor.show.connect (() => {
+                        window_actor.disconnect (show_handler);
+                        callback (window_actor);
+                    });
                 }
 
                 return Source.REMOVE;

src/WindowManager.vala

@@ -2120,9 +2120,10 @@ namespace Gala {
             // TODO: currently only notifications are handled here, other windows should be too
             switch_workspace_window_created_id = window_created.connect ((window) => {
                 if (NotificationStack.is_notification (window)) {
-                    unowned var actor = (Meta.WindowActor) window.get_compositor_private ();
-                    clutter_actor_reparent (actor, notification_group);
-                    notification_stack.show_notification (actor);
+                    InternalUtils.wait_for_window_actor (window, (actor) => {
+                        clutter_actor_reparent (actor, notification_group);
+                        notification_stack.show_notification (actor);
+                    });
                 }
             });