From bf91e2b4ca1ef8b0478d1edec46bd33065457153 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Wed, 29 Nov 2017 18:05:27 -0500
Subject: [PATCH] compositor: reset top_window_actor and remove it from windows
 when destroyed

When the top window actor is destroyed, we need to make sure that
all its references are removed or it could be picked again in next
windows sync, causing crashes.
Since the window might or might not be destroyed when removed (depending
weather animations are in progress over it or not), it's just safer
to wait it to be destroyed before cleaning up any of its reference.

https://bugzilla.gnome.org/show_bug.cgi?id=791006
---
 src/compositor/compositor.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 0eb54fd4e..ff919e6de 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -674,9 +674,6 @@ meta_compositor_remove_window (MetaCompositor *compositor,
   if (compositor->unredirected_window == window)
     set_unredirected_window (compositor, NULL);
 
-  if (compositor->top_window_actor == window_actor)
-    compositor->top_window_actor = NULL;
-
   meta_window_actor_destroy (window_actor);
 }
 
@@ -955,6 +952,16 @@ get_top_visible_window_actor (MetaCompositor *compositor)
   return NULL;
 }
 
+static void
+on_top_window_actor_destroyed (MetaWindowActor *window_actor,
+                               MetaCompositor  *compositor)
+{
+  compositor->top_window_actor = NULL;
+  compositor->windows = g_list_remove (compositor->windows, window_actor);
+
+  meta_stack_tracker_queue_sync_stack (compositor->display->screen->stack_tracker);
+}
+
 void
 meta_compositor_sync_stack (MetaCompositor  *compositor,
 			    GList	    *stack)
@@ -1042,7 +1049,17 @@ meta_compositor_sync_stack (MetaCompositor  *compositor,
 
   sync_actor_stacking (compositor);
 
+  if (compositor->top_window_actor)
+    g_signal_handlers_disconnect_by_func (compositor->top_window_actor,
+                                          on_top_window_actor_destroyed,
+                                          compositor);
+
   compositor->top_window_actor = get_top_visible_window_actor (compositor);
+
+  if (compositor->top_window_actor)
+    g_signal_connect (compositor->top_window_actor, "destroy",
+                      G_CALLBACK (on_top_window_actor_destroyed),
+                      compositor);
 }
 
 void