[clutter] gdk: stage: destroy and clear subsurface on unrealize()

[Olivier Fourdan <ofourdan src gnome org>]

commit 03c7b026685effb897aced7db4bbef8705e21338
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Tue May 9 14:58:50 2017 +0200

    gdk: stage: destroy and clear subsurface on unrealize()
    
    When using a gdk subsurface, destroy it on clutter_stage_gdk_unrealize()
    to avoid keeping around an old existing subsurface pointing to a parent
    surface which might be gone.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781975

 clutter/gdk/clutter-stage-gdk.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/clutter/gdk/clutter-stage-gdk.c b/clutter/gdk/clutter-stage-gdk.c
index 0a40a5e..4b90d5c 100644
--- a/clutter/gdk/clutter-stage-gdk.c
+++ b/clutter/gdk/clutter-stage-gdk.c
@@ -208,6 +208,15 @@ clutter_stage_gdk_unrealize (ClutterStageWindow *stage_window)
       stage_gdk->window = NULL;
     }
 
+#if defined(GDK_WINDOWING_WAYLAND) && defined(COGL_HAS_EGL_PLATFORM_WAYLAND_SUPPORT)
+  /* Destroy and clear subsurface as well */
+  if (GDK_IS_WAYLAND_WINDOW (stage_gdk->subsurface))
+    {
+      gdk_window_destroy (stage_gdk->subsurface);
+      stage_gdk->subsurface = NULL;
+    }
+#endif
+
   clutter_stage_window_parent_iface->unrealize (stage_window);
 }