[mutter/gnome-3-28] screen: Destroy window actors after windows while unmanaging compositor

[Marco Trevisan <marcotrevi src gnome org>]

commit 0ca9d889260bf8d2bb29bcfe5809a199e9372095
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Tue Jun 25 20:22:23 2019 +0200

    screen: Destroy window actors after windows while unmanaging compositor
    
    After commit 2e64457f4 we destroy window actors as part of compositor
    destruction, however this might emit 'actor-removed' signals on window groups
    that the shell could use to access to resources that are already free'd at this
    point (like the destroyed screen, in gnome-shell's Panel._updateSolidStyle()).
    
    So, move the actor destructions under in a new function and destroy the window
    actors as part of compositor unmanage step, just after that all the windows are
    unmanaged (as they need to have an actor around).
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/issues/652

 src/compositor/compositor-private.h |  2 ++
 src/compositor/compositor.c         | 30 +++++++++++++++++-------------
 src/core/screen.c                   |  3 +++
 3 files changed, 22 insertions(+), 13 deletions(-)
---
diff --git a/src/compositor/compositor-private.h b/src/compositor/compositor-private.h
index 4669bc5cb..4582792d4 100644
--- a/src/compositor/compositor-private.h
+++ b/src/compositor/compositor-private.h
@@ -73,4 +73,6 @@ MetaCloseDialog * meta_compositor_create_close_dialog (MetaCompositor *composito
 MetaInhibitShortcutsDialog * meta_compositor_create_inhibit_shortcuts_dialog (MetaCompositor *compositor,
                                                                               MetaWindow     *window);
 
+void meta_compositor_unmanage_window_actors (MetaCompositor *compositor);
+
 #endif /* META_COMPOSITOR_PRIVATE_H */
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 2545d2c0e..6d045339c 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -145,19 +145,6 @@ meta_compositor_destroy (MetaCompositor *compositor)
   clutter_threads_remove_repaint_func (compositor->pre_paint_func_id);
   clutter_threads_remove_repaint_func (compositor->post_paint_func_id);
 
-  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 = NULL;
-    }
-
-  g_clear_pointer (&compositor->window_group, clutter_actor_destroy);
-  g_clear_pointer (&compositor->top_window_group, clutter_actor_destroy);
-  g_clear_pointer (&compositor->feedback_group, clutter_actor_destroy);
-  g_clear_pointer (&compositor->windows, g_list_free);
-
   if (compositor->have_x11_sync_object)
     meta_sync_ring_destroy ();
 }
@@ -610,6 +597,23 @@ meta_compositor_unmanage (MetaCompositor *compositor)
     }
 }
 
+void
+meta_compositor_unmanage_window_actors (MetaCompositor *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 = NULL;
+    }
+
+  g_clear_pointer (&compositor->window_group, clutter_actor_destroy);
+  g_clear_pointer (&compositor->top_window_group, clutter_actor_destroy);
+  g_clear_pointer (&compositor->feedback_group, clutter_actor_destroy);
+  g_clear_pointer (&compositor->windows, g_list_free);
+}
+
 /**
  * meta_shape_cow_for_window:
  * @compositor: A #MetaCompositor
diff --git a/src/core/screen.c b/src/core/screen.c
index d7623f3fb..2e59754d1 100644
--- a/src/core/screen.c
+++ b/src/core/screen.c
@@ -41,6 +41,7 @@
 #include "stack.h"
 #include <meta/compositor.h>
 #include <meta/meta-enum-types.h>
+#include "compositor-private.h"
 #include "core.h"
 #include "meta-cursor-tracker-private.h"
 #include "boxes-private.h"
@@ -844,6 +845,8 @@ meta_screen_free (MetaScreen *screen,
 
   meta_display_unmanage_windows_for_screen (display, screen, timestamp);
 
+  meta_compositor_unmanage_window_actors (display->compositor);
+
   meta_prefs_remove_listener (prefs_changed_callback, screen);
 
   meta_screen_ungrab_keys (screen);