[mutter/wayland] MetaWindowGroup: fix paint volume

[Owen Taylor <otaylor src gnome org>]

commit a796938b3991535ac9b5e79436ce1dbf1da72904
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Tue Dec 3 00:27:03 2013 -0500

    MetaWindowGroup: fix paint volume
    
    In the past, MetaWindowGroup was allocated the size of the screen and
    painted the size of the screen because it contained the screen background,
    but now we also have the "top window group" which contains only popup
    windows, so the allocation doesn't properly reflect the paint bounds
    of the window group. Compute the paint bounds accurately from the
    children.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=719669

 src/compositor/meta-window-group.c |   23 +++++++++++++++++++++--
 1 files changed, 21 insertions(+), 2 deletions(-)
---
diff --git a/src/compositor/meta-window-group.c b/src/compositor/meta-window-group.c
index f76b2e0..9554571 100644
--- a/src/compositor/meta-window-group.c
+++ b/src/compositor/meta-window-group.c
@@ -202,11 +202,30 @@ meta_window_group_paint (ClutterActor *actor)
   meta_cullable_reset_culling (META_CULLABLE (window_group));
 }
 
+/* Adapted from clutter_actor_update_default_paint_volume() */
 static gboolean
-meta_window_group_get_paint_volume (ClutterActor       *actor,
+meta_window_group_get_paint_volume (ClutterActor       *self,
                                     ClutterPaintVolume *volume)
 {
-  return clutter_paint_volume_set_from_allocation (volume, actor);
+  ClutterActorIter iter;
+  ClutterActor *child;
+
+  clutter_actor_iter_init (&iter, self);
+  while (clutter_actor_iter_next (&iter, &child))
+    {
+      const ClutterPaintVolume *child_volume;
+
+      if (!CLUTTER_ACTOR_IS_MAPPED (child))
+        continue;
+
+      child_volume = clutter_actor_get_transformed_paint_volume (child, self);
+      if (child_volume == NULL)
+        return FALSE;
+
+      clutter_paint_volume_union (volume, child_volume);
+    }
+
+  return TRUE;
 }
 
 static void