[mutter] x11/nested: Only paint monitor stage views when enabled

[Jonas Ådahl <jadahl src gnome org>]

commit cc4a65fe948658a5187394d1e1386fde3bec829e
Author: Jonas Ådahl <jadahl gmail com>
Date:   Mon Jul 25 15:28:06 2016 +0800

    x11/nested: Only paint monitor stage views when enabled
    
    Only paint the per monitor stage views when enabled, otherwise bad
    things happen.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768976

 src/backends/x11/meta-backend-x11.c      |    3 ++-
 src/backends/x11/meta-stage-x11-nested.c |   11 ++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)
---
diff --git a/src/backends/x11/meta-backend-x11.c b/src/backends/x11/meta-backend-x11.c
index 24aaca3..c9a6b9a 100644
--- a/src/backends/x11/meta-backend-x11.c
+++ b/src/backends/x11/meta-backend-x11.c
@@ -817,7 +817,8 @@ meta_backend_x11_update_screen_size (MetaBackend *backend,
       ClutterActor *stage = meta_backend_get_stage (backend);
       MetaRenderer *renderer = meta_backend_get_renderer (backend);
 
-      meta_renderer_rebuild_views (renderer);
+      if (meta_is_stage_views_enabled ())
+        meta_renderer_rebuild_views (renderer);
       clutter_actor_set_size (stage, width, height);
     }
   else
diff --git a/src/backends/x11/meta-stage-x11-nested.c b/src/backends/x11/meta-stage-x11-nested.c
index c9dee09..9777191 100644
--- a/src/backends/x11/meta-stage-x11-nested.c
+++ b/src/backends/x11/meta-stage-x11-nested.c
@@ -66,7 +66,10 @@ meta_stage_x11_nested_get_views (ClutterStageWindow *stage_window)
   MetaBackend *backend = meta_get_backend ();
   MetaRenderer *renderer = meta_backend_get_renderer (backend);
 
-  return meta_renderer_get_views (renderer);
+  if (meta_is_stage_views_enabled ())
+    return meta_renderer_get_views (renderer);
+  else
+    return clutter_stage_window_parent_iface->get_views (stage_window);
 }
 
 static void
@@ -80,6 +83,12 @@ meta_stage_x11_nested_finish_frame (ClutterStageWindow *stage_window)
   CoglFramebuffer *onscreen = COGL_FRAMEBUFFER (stage_x11->onscreen);
   GList *l;
 
+  /*
+   * If we are in legacy mode, the stage is already on the onscreen.
+   */
+  if (!meta_is_stage_views_enabled ())
+    return;
+
   if (!stage_nested->pipeline)
     stage_nested->pipeline = cogl_pipeline_new (clutter_backend->cogl_context);