[mutter] window-actor/wayland: Remove subsurface actors on dispose

[Marge Bot <marge-bot src gnome org>]

commit dd416dd3e2eecfe1f0d3c396d0c5b323ce493168
Author: Robert Mader <robert mader posteo de>
Date:   Fri Aug 6 13:09:04 2021 +0200

    window-actor/wayland: Remove subsurface actors on dispose
    
    Destroying the window actor also destroys all its children. Subsurfaces
    however may get reused. If the client did not unparent them before
    the window actor got destroyed, they will be left without actor
    which results in a crash.
    
    Unparent all actors of subsurfaces on dispose to avoid that.
    
    Closes https://gitlab.gnome.org/GNOME/mutter/-/issues/1892
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1958>

 src/compositor/meta-window-actor-wayland.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
---
diff --git a/src/compositor/meta-window-actor-wayland.c b/src/compositor/meta-window-actor-wayland.c
index b1fe616415..641c924db3 100644
--- a/src/compositor/meta-window-actor-wayland.c
+++ b/src/compositor/meta-window-actor-wayland.c
@@ -149,10 +149,33 @@ meta_window_actor_wayland_can_freeze_commits (MetaWindowActor *actor)
   return FALSE;
 }
 
+static void
+meta_window_actor_wayland_dispose (GObject *object)
+{
+  MetaWindowActor *window_actor = META_WINDOW_ACTOR (object);
+  MetaSurfaceActor *surface_actor =
+    meta_window_actor_get_surface (window_actor);
+  GList *children;
+  GList *l;
+
+  children = clutter_actor_get_children (CLUTTER_ACTOR (window_actor));
+  for (l = children; l; l = l->next)
+    {
+      ClutterActor *child_actor = l->data;
+
+      if (META_IS_SURFACE_ACTOR_WAYLAND (child_actor) &&
+          child_actor != CLUTTER_ACTOR (surface_actor))
+        clutter_actor_remove_child (CLUTTER_ACTOR (window_actor), child_actor);
+    }
+
+  G_OBJECT_CLASS (meta_window_actor_wayland_parent_class)->dispose (object);
+}
+
 static void
 meta_window_actor_wayland_class_init (MetaWindowActorWaylandClass *klass)
 {
   MetaWindowActorClass *window_actor_class = META_WINDOW_ACTOR_CLASS (klass);
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
   window_actor_class->assign_surface_actor = meta_window_actor_wayland_assign_surface_actor;
   window_actor_class->frame_complete = meta_window_actor_wayland_frame_complete;
@@ -163,6 +186,8 @@ meta_window_actor_wayland_class_init (MetaWindowActorWaylandClass *klass)
   window_actor_class->set_frozen = meta_window_actor_wayland_set_frozen;
   window_actor_class->update_regions = meta_window_actor_wayland_update_regions;
   window_actor_class->can_freeze_commits = meta_window_actor_wayland_can_freeze_commits;
+
+  object_class->dispose = meta_window_actor_wayland_dispose;
 }
 
 static void