[mutter/gbsneto/cleanup-x11-from-window-actor: 2/10] window-actor: Turn into a derivable class

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 60f7ff3a69255468974154d84fa5a06547314907
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Fri Dec 21 18:12:49 2018 -0200

    window-actor: Turn into a derivable class
    
    We will introduce specialized MetaWindowActors for X11
    and Wayland in the future, so it needs to be derivable.
    
    Make it a derivable class, and introduce a private field.
    The MetaWindowActorClass definition is in the private
    header in order to prevent external consumers of Mutter
    to create MetaWindowActor implementations of their own.
    That is, MetaWindowActor is only internally derivable.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/368

 src/compositor/meta-window-actor-private.h |   5 +
 src/compositor/meta-window-actor.c         | 644 ++++++++++++++++++-----------
 src/meta/meta-window-actor.h               |   9 +-
 3 files changed, 408 insertions(+), 250 deletions(-)
---
diff --git a/src/compositor/meta-window-actor-private.h b/src/compositor/meta-window-actor-private.h
index 66bed4e27..af371afd7 100644
--- a/src/compositor/meta-window-actor-private.h
+++ b/src/compositor/meta-window-actor-private.h
@@ -9,6 +9,11 @@
 #include "compositor/meta-surface-actor.h"
 #include "meta/compositor-mutter.h"
 
+struct _MetaWindowActorClass
+{
+  ClutterActorClass parent;
+};
+
 MetaWindowActor *meta_window_actor_new (MetaWindow *window);
 
 void meta_window_actor_queue_destroy   (MetaWindowActor *self);
diff --git a/src/compositor/meta-window-actor.c b/src/compositor/meta-window-actor.c
index 237aa3c6c..78ad6ded7 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -47,7 +47,7 @@ typedef enum {
   EMITTED_FIRST_FRAME
 } FirstFrameState;
 
-struct _MetaWindowActor
+typedef struct _MetaWindowActorPrivate
 {
   ClutterActor           parent;
 
@@ -118,7 +118,7 @@ struct _MetaWindowActor
 
   guint             updates_frozen         : 1;
   guint             first_frame_state      : 2; /* FirstFrameState */
-};
+} MetaWindowActorPrivate;
 
 typedef struct _FrameData FrameData;
 
@@ -192,6 +192,7 @@ static void cullable_iface_init (MetaCullableInterface *iface);
 static void screen_cast_window_iface_init (MetaScreenCastWindowInterface *iface);
 
 G_DEFINE_TYPE_WITH_CODE (MetaWindowActor, meta_window_actor, CLUTTER_TYPE_ACTOR,
+                         G_ADD_PRIVATE (MetaWindowActor)
                          G_IMPLEMENT_INTERFACE (META_TYPE_CULLABLE, cullable_iface_init)
                          G_IMPLEMENT_INTERFACE (META_TYPE_SCREEN_CAST_WINDOW, 
screen_cast_window_iface_init));
 
@@ -292,7 +293,6 @@ meta_window_actor_class_init (MetaWindowActorClass *klass)
 static void
 meta_window_actor_init (MetaWindowActor *self)
 {
-  self->shadow_class = NULL;
 }
 
 static void
@@ -317,19 +317,24 @@ surface_repaint_scheduled (MetaSurfaceActor *actor,
                            gpointer          user_data)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (user_data);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
 
-  self->repaint_scheduled = TRUE;
+  priv->repaint_scheduled = TRUE;
 }
 
 static gboolean
 is_argb32 (MetaWindowActor *self)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
   /* assume we're argb until we get the window (because
      in practice we're drawing nothing, so we're fully
      transparent)
   */
-  if (self->surface)
-    return meta_surface_actor_is_argb32 (self->surface);
+  if (priv->surface)
+    return meta_surface_actor_is_argb32 (priv->surface);
   else
     return TRUE;
 }
@@ -337,7 +342,9 @@ is_argb32 (MetaWindowActor *self)
 static gboolean
 is_non_opaque (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
 
   return is_argb32 (self) || (window->opacity != 0xFF);
 }
@@ -345,26 +352,35 @@ is_non_opaque (MetaWindowActor *self)
 static gboolean
 is_frozen (MetaWindowActor *self)
 {
-  return self->surface == NULL || self->freeze_count > 0;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  return priv->surface == NULL || priv->freeze_count > 0;
 }
 
 static void
 meta_window_actor_freeze (MetaWindowActor *self)
 {
-  if (self->freeze_count == 0 && self->surface)
-    meta_surface_actor_set_frozen (self->surface, TRUE);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->freeze_count == 0 && priv->surface)
+    meta_surface_actor_set_frozen (priv->surface, TRUE);
 
-  self->freeze_count ++;
+  priv->freeze_count ++;
 }
 
 static void
 meta_window_actor_sync_thawed_state (MetaWindowActor *self)
 {
-  if (self->first_frame_state == INITIALLY_FROZEN)
-    self->first_frame_state = DRAWING_FIRST_FRAME;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
 
-  if (self->surface)
-    meta_surface_actor_set_frozen (self->surface, FALSE);
+  if (priv->first_frame_state == INITIALLY_FROZEN)
+    priv->first_frame_state = DRAWING_FIRST_FRAME;
+
+  if (priv->surface)
+    meta_surface_actor_set_frozen (priv->surface, FALSE);
 
   /* We sometimes ignore moves and resizes on frozen windows */
   meta_window_actor_sync_actor_geometry (self, FALSE);
@@ -373,11 +389,14 @@ meta_window_actor_sync_thawed_state (MetaWindowActor *self)
 static void
 meta_window_actor_thaw (MetaWindowActor *self)
 {
-  if (self->freeze_count <= 0)
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->freeze_count <= 0)
     g_error ("Error in freeze/thaw accounting");
 
-  self->freeze_count--;
-  if (self->freeze_count > 0)
+  priv->freeze_count--;
+  if (priv->freeze_count > 0)
     return;
 
   /* We still might be frozen due to lack of a MetaSurfaceActor */
@@ -395,30 +414,33 @@ static void
 set_surface (MetaWindowActor  *self,
              MetaSurfaceActor *surface)
 {
-  if (self->surface)
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->surface)
     {
-      g_signal_handler_disconnect (self->surface, self->repaint_scheduled_id);
-      g_signal_handler_disconnect (self->surface, self->size_changed_id);
-      self->repaint_scheduled_id = 0;
-      clutter_actor_remove_child (CLUTTER_ACTOR (self), CLUTTER_ACTOR (self->surface));
-      g_object_unref (self->surface);
+      g_signal_handler_disconnect (priv->surface, priv->repaint_scheduled_id);
+      g_signal_handler_disconnect (priv->surface, priv->size_changed_id);
+      priv->repaint_scheduled_id = 0;
+      clutter_actor_remove_child (CLUTTER_ACTOR (self), CLUTTER_ACTOR (priv->surface));
+      g_object_unref (priv->surface);
     }
 
-  self->surface = surface;
+  priv->surface = surface;
 
-  if (self->surface)
+  if (priv->surface)
     {
-      g_object_ref_sink (self->surface);
-      self->repaint_scheduled_id = g_signal_connect (self->surface, "repaint-scheduled",
+      g_object_ref_sink (priv->surface);
+      priv->repaint_scheduled_id = g_signal_connect (priv->surface, "repaint-scheduled",
                                                      G_CALLBACK (surface_repaint_scheduled), self);
-      self->size_changed_id = g_signal_connect (self->surface, "size-changed",
+      priv->size_changed_id = g_signal_connect (priv->surface, "size-changed",
                                                 G_CALLBACK (surface_size_changed), self);
-      clutter_actor_add_child (CLUTTER_ACTOR (self), CLUTTER_ACTOR (self->surface));
+      clutter_actor_add_child (CLUTTER_ACTOR (self), CLUTTER_ACTOR (priv->surface));
 
       meta_window_actor_update_shape (self);
 
       if (is_frozen (self))
-        meta_surface_actor_set_frozen (self->surface, TRUE);
+        meta_surface_actor_set_frozen (priv->surface, TRUE);
       else
         meta_window_actor_sync_thawed_state (self);
     }
@@ -427,7 +449,9 @@ set_surface (MetaWindowActor  *self,
 void
 meta_window_actor_update_surface (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
   MetaSurfaceActor *surface_actor;
 
 #ifdef HAVE_WAYLAND
@@ -447,9 +471,11 @@ static void
 meta_window_actor_constructed (GObject *object)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (object);
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
 
-  self->compositor = window->display->compositor;
+  priv->compositor = window->display->compositor;
 
   meta_window_actor_update_surface (self);
 
@@ -457,37 +483,39 @@ meta_window_actor_constructed (GObject *object)
 
   /* Start off with an empty shape region to maintain the invariant
    * that it's always set */
-  self->shape_region = cairo_region_create ();
+  priv->shape_region = cairo_region_create ();
 }
 
 static void
 meta_window_actor_dispose (GObject *object)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (object);
-  MetaCompositor *compositor = self->compositor;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaCompositor *compositor = priv->compositor;
 
-  if (self->disposed)
+  if (priv->disposed)
     return;
 
-  self->disposed = TRUE;
+  priv->disposed = TRUE;
 
-  if (self->send_frame_messages_timer != 0)
+  if (priv->send_frame_messages_timer != 0)
     {
-      g_source_remove (self->send_frame_messages_timer);
-      self->send_frame_messages_timer = 0;
+      g_source_remove (priv->send_frame_messages_timer);
+      priv->send_frame_messages_timer = 0;
     }
 
-  g_clear_pointer (&self->shape_region, cairo_region_destroy);
-  g_clear_pointer (&self->shadow_clip, cairo_region_destroy);
+  g_clear_pointer (&priv->shape_region, cairo_region_destroy);
+  g_clear_pointer (&priv->shadow_clip, cairo_region_destroy);
 
-  g_clear_pointer (&self->shadow_class, g_free);
-  g_clear_pointer (&self->focused_shadow, meta_shadow_unref);
-  g_clear_pointer (&self->unfocused_shadow, meta_shadow_unref);
-  g_clear_pointer (&self->shadow_shape, meta_window_shape_unref);
+  g_clear_pointer (&priv->shadow_class, g_free);
+  g_clear_pointer (&priv->focused_shadow, meta_shadow_unref);
+  g_clear_pointer (&priv->unfocused_shadow, meta_shadow_unref);
+  g_clear_pointer (&priv->shadow_shape, meta_window_shape_unref);
 
   compositor->windows = g_list_remove (compositor->windows, (gconstpointer) self);
 
-  g_clear_object (&self->window);
+  g_clear_object (&priv->window);
 
   set_surface (self, NULL);
 
@@ -497,9 +525,11 @@ meta_window_actor_dispose (GObject *object)
 static void
 meta_window_actor_finalize (GObject *object)
 {
-  MetaWindowActor        *self = META_WINDOW_ACTOR (object);
+  MetaWindowActor *self = META_WINDOW_ACTOR (object);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
 
-  g_list_free_full (self->frames, (GDestroyNotify) frame_data_free);
+  g_list_free_full (priv->frames, (GDestroyNotify) frame_data_free);
 
   G_OBJECT_CLASS (meta_window_actor_parent_class)->finalize (object);
 }
@@ -511,22 +541,24 @@ meta_window_actor_set_property (GObject      *object,
                                 GParamSpec   *pspec)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (object);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
 
   switch (prop_id)
     {
     case PROP_META_WINDOW:
-      self->window = g_value_dup_object (value);
-      g_signal_connect_object (self->window, "notify::appears-focused",
+      priv->window = g_value_dup_object (value);
+      g_signal_connect_object (priv->window, "notify::appears-focused",
                                G_CALLBACK (window_appears_focused_notify), self, 0);
       break;
     case PROP_SHADOW_MODE:
       {
         MetaShadowMode newv = g_value_get_enum (value);
 
-        if (newv == self->shadow_mode)
+        if (newv == priv->shadow_mode)
           return;
 
-        self->shadow_mode = newv;
+        priv->shadow_mode = newv;
 
         meta_window_actor_invalidate_shadow (self);
       }
@@ -535,11 +567,11 @@ meta_window_actor_set_property (GObject      *object,
       {
         const char *newv = g_value_get_string (value);
 
-        if (g_strcmp0 (newv, self->shadow_class) == 0)
+        if (g_strcmp0 (newv, priv->shadow_class) == 0)
           return;
 
-        g_free (self->shadow_class);
-        self->shadow_class = g_strdup (newv);
+        g_free (priv->shadow_class);
+        priv->shadow_class = g_strdup (newv);
 
         meta_window_actor_invalidate_shadow (self);
       }
@@ -557,17 +589,19 @@ meta_window_actor_get_property (GObject      *object,
                                 GParamSpec   *pspec)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (object);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
 
   switch (prop_id)
     {
     case PROP_META_WINDOW:
-      g_value_set_object (value, self->window);
+      g_value_set_object (value, priv->window);
       break;
     case PROP_SHADOW_MODE:
-      g_value_set_enum (value, self->shadow_mode);
+      g_value_set_enum (value, priv->shadow_mode);
       break;
     case PROP_SHADOW_CLASS:
-      g_value_set_string (value, self->shadow_class);
+      g_value_set_string (value, priv->shadow_class);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -578,11 +612,14 @@ meta_window_actor_get_property (GObject      *object,
 static const char *
 meta_window_actor_get_shadow_class (MetaWindowActor *self)
 {
-  if (self->shadow_class != NULL)
-    return self->shadow_class;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->shadow_class != NULL)
+    return priv->shadow_class;
   else
     {
-      MetaWindowType window_type = meta_window_get_window_type (self->window);
+      MetaWindowType window_type = meta_window_get_window_type (priv->window);
 
       switch (window_type)
         {
@@ -593,7 +630,7 @@ meta_window_actor_get_shadow_class (MetaWindowActor *self)
           return "popup-menu";
         default:
           {
-            MetaFrameType frame_type = meta_window_get_frame_type (self->window);
+            MetaFrameType frame_type = meta_window_get_frame_type (priv->window);
             return meta_frame_type_to_string (frame_type);
           }
         }
@@ -616,7 +653,10 @@ void
 meta_window_actor_get_shape_bounds (MetaWindowActor       *self,
                                     cairo_rectangle_int_t *bounds)
 {
-  cairo_region_get_extents (self->shape_region, bounds);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  cairo_region_get_extents (priv->shape_region, bounds);
 }
 
 static void
@@ -624,11 +664,13 @@ meta_window_actor_get_shadow_bounds (MetaWindowActor       *self,
                                      gboolean               appears_focused,
                                      cairo_rectangle_int_t *bounds)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   MetaShadow *shadow;
   cairo_rectangle_int_t shape_bounds;
   MetaShadowParams params;
 
-  shadow = appears_focused ? self->focused_shadow : self->unfocused_shadow;
+  shadow = appears_focused ? priv->focused_shadow : priv->unfocused_shadow;
 
   meta_window_actor_get_shape_bounds (self, &shape_bounds);
   meta_window_actor_get_shadow_params (self, appears_focused, &params);
@@ -656,23 +698,28 @@ meta_window_actor_get_shadow_bounds (MetaWindowActor       *self,
 static gboolean
 clip_shadow_under_window (MetaWindowActor *self)
 {
-  return is_non_opaque (self) && self->window->frame;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  return is_non_opaque (self) && priv->window->frame;
 }
 
 static void
 assign_frame_counter_to_frames (MetaWindowActor *self)
 {
-  MetaCompositor *compositor = self->compositor;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaCompositor *compositor = priv->compositor;
   ClutterStage *stage = CLUTTER_STAGE (compositor->stage);
   GList *l;
 
   /* If the window is obscured, then we're expecting to deal with sending
    * frame messages in a timeout, rather than in this paint cycle.
    */
-  if (self->send_frame_messages_timer != 0)
+  if (priv->send_frame_messages_timer != 0)
     return;
 
-  for (l = self->frames; l; l = l->next)
+  for (l = priv->frames; l; l = l->next)
     {
       FrameData *frame = l->data;
 
@@ -685,20 +732,22 @@ static void
 meta_window_actor_paint (ClutterActor *actor)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (actor);
-  gboolean appears_focused = meta_window_appears_focused (self->window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  gboolean appears_focused = meta_window_appears_focused (priv->window);
   MetaShadow *shadow;
   CoglFramebuffer *framebuffer = cogl_get_draw_framebuffer ();
 
-  shadow = appears_focused ? self->focused_shadow : self->unfocused_shadow;
+  shadow = appears_focused ? priv->focused_shadow : priv->unfocused_shadow;
 
  /* This window got damage when obscured; we set up a timer
   * to send frame completion events, but since we're drawing
   * the window now (for some other reason) cancel the timer
   * and send the completion events normally */
-  if (self->send_frame_messages_timer != 0)
+  if (priv->send_frame_messages_timer != 0)
     {
-      g_source_remove (self->send_frame_messages_timer);
-      self->send_frame_messages_timer = 0;
+      g_source_remove (priv->send_frame_messages_timer);
+      priv->send_frame_messages_timer = 0;
 
       assign_frame_counter_to_frames (self);
     }
@@ -707,18 +756,18 @@ meta_window_actor_paint (ClutterActor *actor)
     {
       MetaShadowParams params;
       cairo_rectangle_int_t shape_bounds;
-      cairo_region_t *clip = self->shadow_clip;
-      MetaWindow *window = self->window;
+      cairo_region_t *clip = priv->shadow_clip;
+      MetaWindow *window = priv->window;
 
       meta_window_actor_get_shape_bounds (self, &shape_bounds);
       meta_window_actor_get_shadow_params (self, appears_focused, &params);
 
-      /* The frame bounds are already subtracted from self->shadow_clip
+      /* The frame bounds are already subtracted from priv->shadow_clip
        * if that exists.
        */
       if (!clip && clip_shadow_under_window (self))
         {
-          cairo_region_t *frame_bounds = meta_window_get_frame_bounds (self->window);
+          cairo_region_t *frame_bounds = meta_window_get_frame_bounds (priv->window);
           cairo_rectangle_int_t bounds;
 
           meta_window_actor_get_shadow_bounds (self, appears_focused, &bounds);
@@ -737,7 +786,7 @@ meta_window_actor_paint (ClutterActor *actor)
                          clip,
                          clip_shadow_under_window (self)); /* clip_strictly - not just as an optimization */
 
-      if (clip && clip != self->shadow_clip)
+      if (clip && clip != priv->shadow_clip)
         cairo_region_destroy (clip);
     }
 
@@ -749,13 +798,15 @@ meta_window_actor_get_paint_volume (ClutterActor       *actor,
                                     ClutterPaintVolume *volume)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (actor);
-  gboolean appears_focused = meta_window_appears_focused (self->window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  gboolean appears_focused = meta_window_appears_focused (priv->window);
 
   /* The paint volume is computed before paint functions are called
    * so our bounds might not be updated yet. Force an update. */
   meta_window_actor_handle_updates (self);
 
-  if (appears_focused ? self->focused_shadow : self->unfocused_shadow)
+  if (appears_focused ? priv->focused_shadow : priv->unfocused_shadow)
     {
       cairo_rectangle_int_t shadow_bounds;
       ClutterActorBox shadow_box;
@@ -776,11 +827,11 @@ meta_window_actor_get_paint_volume (ClutterActor       *actor,
       clutter_paint_volume_union_box (volume, &shadow_box);
     }
 
-  if (self->surface)
+  if (priv->surface)
     {
       const ClutterPaintVolume *child_volume;
 
-      child_volume = clutter_actor_get_transformed_paint_volume (CLUTTER_ACTOR (self->surface), actor);
+      child_volume = clutter_actor_get_transformed_paint_volume (CLUTTER_ACTOR (priv->surface), actor);
       if (!child_volume)
         return FALSE;
 
@@ -793,30 +844,33 @@ meta_window_actor_get_paint_volume (ClutterActor       *actor,
 static gboolean
 meta_window_actor_has_shadow (MetaWindowActor *self)
 {
-  if (self->shadow_mode == META_SHADOW_MODE_FORCED_OFF)
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->shadow_mode == META_SHADOW_MODE_FORCED_OFF)
     return FALSE;
-  if (self->shadow_mode == META_SHADOW_MODE_FORCED_ON)
+  if (priv->shadow_mode == META_SHADOW_MODE_FORCED_ON)
     return TRUE;
 
   /* Leaving out shadows for maximized and fullscreen windows is an effeciency
    * win and also prevents the unsightly effect of the shadow of maximized
    * window appearing on an adjacent window */
-  if ((meta_window_get_maximized (self->window) == META_MAXIMIZE_BOTH) ||
-      meta_window_is_fullscreen (self->window))
+  if ((meta_window_get_maximized (priv->window) == META_MAXIMIZE_BOTH) ||
+      meta_window_is_fullscreen (priv->window))
     return FALSE;
 
   /*
    * If we have two snap-tiled windows, we don't want the shadow to obstruct
    * the other window.
    */
-  if (meta_window_get_tile_match (self->window))
+  if (meta_window_get_tile_match (priv->window))
     return FALSE;
 
   /*
    * Always put a shadow around windows with a frame - This should override
    * the restriction about not putting a shadow around ARGB windows.
    */
-  if (meta_window_get_frame (self->window))
+  if (meta_window_get_frame (priv->window))
     return TRUE;
 
   /*
@@ -830,7 +884,7 @@ meta_window_actor_has_shadow (MetaWindowActor *self)
    * If a window specifies that it has custom frame extents, that likely
    * means that it is drawing a shadow itself. Don't draw our own.
    */
-  if (self->window->has_custom_frame_extents)
+  if (priv->window->has_custom_frame_extents)
     return FALSE;
 
   /*
@@ -850,7 +904,10 @@ meta_window_actor_has_shadow (MetaWindowActor *self)
 MetaWindow *
 meta_window_actor_get_meta_window (MetaWindowActor *self)
 {
-  return self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  return priv->window;
 }
 
 /**
@@ -865,8 +922,11 @@ meta_window_actor_get_meta_window (MetaWindowActor *self)
 ClutterActor *
 meta_window_actor_get_texture (MetaWindowActor *self)
 {
-  if (self->surface)
-    return CLUTTER_ACTOR (meta_surface_actor_get_texture (self->surface));
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->surface)
+    return CLUTTER_ACTOR (meta_surface_actor_get_texture (priv->surface));
   else
     return NULL;
 }
@@ -883,7 +943,10 @@ meta_window_actor_get_texture (MetaWindowActor *self)
 MetaSurfaceActor *
 meta_window_actor_get_surface (MetaWindowActor *self)
 {
-  return self->surface;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  return priv->surface;
 }
 
 /**
@@ -897,16 +960,21 @@ meta_window_actor_get_surface (MetaWindowActor *self)
 gboolean
 meta_window_actor_is_destroyed (MetaWindowActor *self)
 {
-  return self->disposed || self->needs_destroy;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  return priv->disposed || priv->needs_destroy;
 }
 
 static gboolean
 send_frame_messages_timeout (gpointer data)
 {
   MetaWindowActor *self = (MetaWindowActor *) data;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   GList *l;
 
-  for (l = self->frames; l;)
+  for (l = priv->frames; l;)
     {
       GList *l_next = l->next;
       FrameData *frame = l->data;
@@ -916,15 +984,15 @@ send_frame_messages_timeout (gpointer data)
           do_send_frame_drawn (self, frame);
           do_send_frame_timings (self, frame, 0, 0);
 
-          self->frames = g_list_delete_link (self->frames, l);
+          priv->frames = g_list_delete_link (priv->frames, l);
           frame_data_free (frame);
         }
 
       l = l_next;
     }
 
-  self->needs_frame_drawn = FALSE;
-  self->send_frame_messages_timer = 0;
+  priv->needs_frame_drawn = FALSE;
+  priv->send_frame_messages_timer = 0;
 
   return FALSE;
 }
@@ -932,14 +1000,16 @@ send_frame_messages_timeout (gpointer data)
 static void
 queue_send_frame_messages_timeout (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
-  MetaDisplay *display = meta_window_get_display (self->window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
+  MetaDisplay *display = meta_window_get_display (priv->window);
   MetaLogicalMonitor *logical_monitor;
   int64_t current_time;
   float refresh_rate;
   int interval, offset;
 
-  if (self->send_frame_messages_timer != 0)
+  if (priv->send_frame_messages_timer != 0)
     return;
 
   logical_monitor = meta_window_get_main_logical_monitor (window);
@@ -963,20 +1033,22 @@ queue_send_frame_messages_timeout (MetaWindowActor *self)
     meta_compositor_monotonic_time_to_server_time (display,
                                                    g_get_monotonic_time ());
   interval = (int)(1000000 / refresh_rate) * 6;
-  offset = MAX (0, self->frame_drawn_time + interval - current_time) / 1000;
+  offset = MAX (0, priv->frame_drawn_time + interval - current_time) / 1000;
 
  /* The clutter master clock source has already been added with META_PRIORITY_REDRAW,
   * so the timer will run *after* the clutter frame handling, if a frame is ready
   * to be drawn when the timer expires.
   */
-  self->send_frame_messages_timer = g_timeout_add_full (META_PRIORITY_REDRAW, offset, 
send_frame_messages_timeout, self, NULL);
-  g_source_set_name_by_id (self->send_frame_messages_timer, "[mutter] send_frame_messages_timeout");
+  priv->send_frame_messages_timer = g_timeout_add_full (META_PRIORITY_REDRAW, offset, 
send_frame_messages_timeout, self, NULL);
+  g_source_set_name_by_id (priv->send_frame_messages_timer, "[mutter] send_frame_messages_timeout");
 }
 
 void
 meta_window_actor_queue_frame_drawn (MetaWindowActor *self,
                                      gboolean         no_delay_frame)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   FrameData *frame;
 
   if (meta_window_actor_is_destroyed (self))
@@ -985,11 +1057,11 @@ meta_window_actor_queue_frame_drawn (MetaWindowActor *self,
   frame = g_slice_new0 (FrameData);
   frame->frame_counter = -1;
 
-  self->needs_frame_drawn = TRUE;
+  priv->needs_frame_drawn = TRUE;
 
-  frame->sync_request_serial = self->window->sync_request_serial;
+  frame->sync_request_serial = priv->window->sync_request_serial;
 
-  self->frames = g_list_prepend (self->frames, frame);
+  priv->frames = g_list_prepend (priv->frames, frame);
 
   if (no_delay_frame)
     {
@@ -997,12 +1069,12 @@ meta_window_actor_queue_frame_drawn (MetaWindowActor *self,
       clutter_stage_skip_sync_delay (CLUTTER_STAGE (stage));
     }
 
-  if (!self->repaint_scheduled)
+  if (!priv->repaint_scheduled)
     {
       gboolean is_obscured;
 
-      if (self->surface)
-        is_obscured = meta_surface_actor_is_obscured (self->surface);
+      if (priv->surface)
+        is_obscured = meta_surface_actor_is_obscured (priv->surface);
       else
         is_obscured = FALSE;
 
@@ -1020,11 +1092,11 @@ meta_window_actor_queue_frame_drawn (MetaWindowActor *self,
         }
       else
         {
-          if (self->surface)
+          if (priv->surface)
             {
               const cairo_rectangle_int_t clip = { 0, 0, 1, 1 };
-              clutter_actor_queue_redraw_with_clip (CLUTTER_ACTOR (self->surface), &clip);
-              self->repaint_scheduled = TRUE;
+              clutter_actor_queue_redraw_with_clip (CLUTTER_ACTOR (priv->surface), &clip);
+              priv->repaint_scheduled = TRUE;
             }
         }
     }
@@ -1033,10 +1105,13 @@ meta_window_actor_queue_frame_drawn (MetaWindowActor *self,
 gboolean
 meta_window_actor_effect_in_progress (MetaWindowActor *self)
 {
-  return (self->minimize_in_progress ||
-          self->size_change_in_progress ||
-          self->map_in_progress ||
-          self->destroy_in_progress);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  return (priv->minimize_in_progress ||
+          priv->size_change_in_progress ||
+          priv->map_in_progress ||
+          priv->destroy_in_progress);
 }
 
 static gboolean
@@ -1057,7 +1132,9 @@ static gboolean
 start_simple_effect (MetaWindowActor  *self,
                      MetaPluginEffect  event)
 {
-  MetaCompositor *compositor = self->compositor;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaCompositor *compositor = priv->compositor;
   gint *counter = NULL;
   gboolean use_freeze_thaw = FALSE;
 
@@ -1068,16 +1145,16 @@ start_simple_effect (MetaWindowActor  *self,
   case META_PLUGIN_NONE:
     return FALSE;
   case META_PLUGIN_MINIMIZE:
-    counter = &self->minimize_in_progress;
+    counter = &priv->minimize_in_progress;
     break;
   case META_PLUGIN_UNMINIMIZE:
-    counter = &self->unminimize_in_progress;
+    counter = &priv->unminimize_in_progress;
     break;
   case META_PLUGIN_MAP:
-    counter = &self->map_in_progress;
+    counter = &priv->map_in_progress;
     break;
   case META_PLUGIN_DESTROY:
-    counter = &self->destroy_in_progress;
+    counter = &priv->destroy_in_progress;
     break;
   case META_PLUGIN_SIZE_CHANGE:
   case META_PLUGIN_SWITCH_WORKSPACE:
@@ -1108,7 +1185,10 @@ start_simple_effect (MetaWindowActor  *self,
 static void
 meta_window_actor_after_effects (MetaWindowActor *self)
 {
-  if (self->needs_destroy)
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->needs_destroy)
     {
       clutter_actor_destroy (CLUTTER_ACTOR (self));
       return;
@@ -1123,11 +1203,13 @@ void
 meta_window_actor_effect_completed (MetaWindowActor  *self,
                                     MetaPluginEffect  event)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   gboolean inconsistent = FALSE;
 
   /* NB: Keep in mind that when effects get completed it possible
    * that the corresponding MetaWindow may have be been destroyed.
-   * In this case self->window will == NULL */
+   * In this case priv->window will == NULL */
 
   switch (event)
   {
@@ -1135,22 +1217,22 @@ meta_window_actor_effect_completed (MetaWindowActor  *self,
     break;
   case META_PLUGIN_MINIMIZE:
     {
-      self->minimize_in_progress--;
-      if (self->minimize_in_progress < 0)
+      priv->minimize_in_progress--;
+      if (priv->minimize_in_progress < 0)
         {
           g_warning ("Error in minimize accounting.");
-          self->minimize_in_progress = 0;
+          priv->minimize_in_progress = 0;
           inconsistent = TRUE;
         }
     }
     break;
   case META_PLUGIN_UNMINIMIZE:
     {
-      self->unminimize_in_progress--;
-      if (self->unminimize_in_progress < 0)
+      priv->unminimize_in_progress--;
+      if (priv->unminimize_in_progress < 0)
        {
          g_warning ("Error in unminimize accounting.");
-         self->unminimize_in_progress = 0;
+         priv->unminimize_in_progress = 0;
          inconsistent = TRUE;
        }
     }
@@ -1160,31 +1242,31 @@ meta_window_actor_effect_completed (MetaWindowActor  *self,
      * Make sure that the actor is at the correct place in case
      * the plugin fscked.
      */
-    self->map_in_progress--;
+    priv->map_in_progress--;
 
-    if (self->map_in_progress < 0)
+    if (priv->map_in_progress < 0)
       {
         g_warning ("Error in map accounting.");
-        self->map_in_progress = 0;
+        priv->map_in_progress = 0;
         inconsistent = TRUE;
       }
     break;
   case META_PLUGIN_DESTROY:
-    self->destroy_in_progress--;
+    priv->destroy_in_progress--;
 
-    if (self->destroy_in_progress < 0)
+    if (priv->destroy_in_progress < 0)
       {
         g_warning ("Error in destroy accounting.");
-        self->destroy_in_progress = 0;
+        priv->destroy_in_progress = 0;
         inconsistent = TRUE;
       }
     break;
   case META_PLUGIN_SIZE_CHANGE:
-    self->size_change_in_progress--;
-    if (self->size_change_in_progress < 0)
+    priv->size_change_in_progress--;
+    if (priv->size_change_in_progress < 0)
       {
         g_warning ("Error in size change accounting.");
-        self->size_change_in_progress = 0;
+        priv->size_change_in_progress = 0;
         inconsistent = TRUE;
       }
     break;
@@ -1203,8 +1285,11 @@ meta_window_actor_effect_completed (MetaWindowActor  *self,
 gboolean
 meta_window_actor_should_unredirect (MetaWindowActor *self)
 {
-  if (!meta_window_actor_is_destroyed (self) && self->surface)
-    return meta_surface_actor_should_unredirect (self->surface);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (!meta_window_actor_is_destroyed (self) && priv->surface)
+    return meta_surface_actor_should_unredirect (priv->surface);
   else
     return FALSE;
 }
@@ -1213,22 +1298,27 @@ void
 meta_window_actor_set_unredirected (MetaWindowActor *self,
                                     gboolean         unredirected)
 {
-  g_assert (self->surface); /* because otherwise should_unredirect() is FALSE */
-  meta_surface_actor_set_unredirected (self->surface, unredirected);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  g_assert (priv->surface); /* because otherwise should_unredirect() is FALSE */
+  meta_surface_actor_set_unredirected (priv->surface, unredirected);
 }
 
 void
 meta_window_actor_queue_destroy (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
   MetaWindowType window_type = meta_window_get_window_type (window);
 
   meta_window_set_compositor_private (window, NULL);
 
-  if (self->send_frame_messages_timer != 0)
+  if (priv->send_frame_messages_timer != 0)
     {
-      g_source_remove (self->send_frame_messages_timer);
-      self->send_frame_messages_timer = 0;
+      g_source_remove (priv->send_frame_messages_timer);
+      priv->send_frame_messages_timer = 0;
     }
 
   if (window_type == META_WINDOW_DROPDOWN_MENU ||
@@ -1246,7 +1336,7 @@ meta_window_actor_queue_destroy (MetaWindowActor *self)
       return;
     }
 
-  self->needs_destroy = TRUE;
+  priv->needs_destroy = TRUE;
 
   if (!meta_window_actor_effect_in_progress (self))
     clutter_actor_destroy (CLUTTER_ACTOR (self));
@@ -1256,14 +1346,16 @@ void
 meta_window_actor_sync_actor_geometry (MetaWindowActor *self,
                                        gboolean         did_placement)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   MetaRectangle window_rect;
 
-  meta_window_get_buffer_rect (self->window, &window_rect);
+  meta_window_get_buffer_rect (priv->window, &window_rect);
 
   /* When running as a Wayland compositor we catch size changes when new
    * buffers are attached */
-  if (META_IS_SURFACE_ACTOR_X11 (self->surface))
-    meta_surface_actor_x11_set_size (META_SURFACE_ACTOR_X11 (self->surface),
+  if (META_IS_SURFACE_ACTOR_X11 (priv->surface))
+    meta_surface_actor_x11_set_size (META_SURFACE_ACTOR_X11 (priv->surface),
                                      window_rect.width, window_rect.height);
 
   /* Normally we want freezing a window to also freeze its position; this allows
@@ -1289,12 +1381,14 @@ void
 meta_window_actor_show (MetaWindowActor   *self,
                         MetaCompEffect     effect)
 {
-  MetaCompositor *compositor = self->compositor;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaCompositor *compositor = priv->compositor;
   MetaPluginEffect event;
 
-  g_return_if_fail (!self->visible);
+  g_return_if_fail (!priv->visible);
 
-  self->visible = TRUE;
+  priv->visible = TRUE;
 
   switch (effect)
     {
@@ -1322,12 +1416,14 @@ void
 meta_window_actor_hide (MetaWindowActor *self,
                         MetaCompEffect   effect)
 {
-  MetaCompositor *compositor = self->compositor;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaCompositor *compositor = priv->compositor;
   MetaPluginEffect event;
 
-  g_return_if_fail (self->visible);
+  g_return_if_fail (priv->visible);
 
-  self->visible = FALSE;
+  priv->visible = FALSE;
 
   /* If a plugin is animating a workspace transition, we have to
    * hold off on hiding the window, and do it after the workspace
@@ -1361,15 +1457,17 @@ meta_window_actor_size_change (MetaWindowActor    *self,
                                MetaRectangle      *old_frame_rect,
                                MetaRectangle      *old_buffer_rect)
 {
-  MetaCompositor *compositor = self->compositor;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaCompositor *compositor = priv->compositor;
 
-  self->size_change_in_progress++;
+  priv->size_change_in_progress++;
   meta_window_actor_freeze (self);
 
   if (!meta_plugin_manager_event_size_change (compositor->plugin_mgr, self,
                                               which_change, old_frame_rect, old_buffer_rect))
     {
-      self->size_change_in_progress--;
+      priv->size_change_in_progress--;
       meta_window_actor_thaw (self);
     }
 }
@@ -1377,6 +1475,7 @@ meta_window_actor_size_change (MetaWindowActor    *self,
 MetaWindowActor *
 meta_window_actor_new (MetaWindow *window)
 {
+  MetaWindowActorPrivate *priv;
   MetaDisplay *display = meta_window_get_display (window);
   MetaCompositor *compositor = display->compositor;
   MetaWindowActor        *self;
@@ -1385,21 +1484,22 @@ meta_window_actor_new (MetaWindow *window)
   self = g_object_new (META_TYPE_WINDOW_ACTOR,
                        "meta-window", window,
                        NULL);
+  priv = meta_window_actor_get_instance_private (self);
 
   meta_window_actor_sync_updates_frozen (self);
 
   if (is_frozen (self))
-    self->first_frame_state = INITIALLY_FROZEN;
+    priv->first_frame_state = INITIALLY_FROZEN;
   else
-    self->first_frame_state = DRAWING_FIRST_FRAME;
+    priv->first_frame_state = DRAWING_FIRST_FRAME;
 
   /* If a window doesn't start off with updates frozen, we should
    * we should send a _NET_WM_FRAME_DRAWN immediately after the first drawn.
    */
-  if (self->window->extended_sync_request_counter && !self->updates_frozen)
+  if (priv->window->extended_sync_request_counter && !priv->updates_frozen)
     meta_window_actor_queue_frame_drawn (self, FALSE);
 
-  meta_window_actor_sync_actor_geometry (self, self->window->placed);
+  meta_window_actor_sync_actor_geometry (self, priv->window->placed);
 
   /* Hang our compositor window state off the MetaWindow for fast retrieval */
   meta_window_set_compositor_private (window, G_OBJECT (self));
@@ -1478,24 +1578,26 @@ static void
 meta_window_actor_set_clip_region_beneath (MetaWindowActor *self,
                                            cairo_region_t  *beneath_region)
 {
-  gboolean appears_focused = meta_window_appears_focused (self->window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  gboolean appears_focused = meta_window_appears_focused (priv->window);
 
-  if (appears_focused ? self->focused_shadow : self->unfocused_shadow)
+  if (appears_focused ? priv->focused_shadow : priv->unfocused_shadow)
     {
-      g_clear_pointer (&self->shadow_clip, cairo_region_destroy);
+      g_clear_pointer (&priv->shadow_clip, cairo_region_destroy);
 
       if (beneath_region)
         {
-          self->shadow_clip = cairo_region_copy (beneath_region);
+          priv->shadow_clip = cairo_region_copy (beneath_region);
 
           if (clip_shadow_under_window (self))
             {
-              cairo_region_t *frame_bounds = meta_window_get_frame_bounds (self->window);
-              cairo_region_subtract (self->shadow_clip, frame_bounds);
+              cairo_region_t *frame_bounds = meta_window_get_frame_bounds (priv->window);
+              cairo_region_subtract (priv->shadow_clip, frame_bounds);
             }
         }
       else
-        self->shadow_clip = NULL;
+        priv->shadow_clip = NULL;
     }
 }
 
@@ -1514,8 +1616,10 @@ static void
 meta_window_actor_reset_culling (MetaCullable *cullable)
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (cullable);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
 
-  g_clear_pointer (&self->shadow_clip, cairo_region_destroy);
+  g_clear_pointer (&priv->shadow_clip, cairo_region_destroy);
 
   meta_cullable_reset_culling_children (cullable);
 }
@@ -1530,6 +1634,8 @@ cullable_iface_init (MetaCullableInterface *iface)
 static void
 check_needs_shadow (MetaWindowActor *self)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   MetaShadow *old_shadow = NULL;
   MetaShadow **shadow_location;
   gboolean recompute_shadow;
@@ -1540,23 +1646,23 @@ check_needs_shadow (MetaWindowActor *self)
    * and avoids the need to explicitly handle window type changes, which
    * we would do if tried to keep track of when we might be adding or removing
    * a shadow more explicitly. We only keep track of changes to the *shape* of
-   * the shadow with self->recompute_shadow.
+   * the shadow with priv->recompute_shadow.
    */
 
   should_have_shadow = meta_window_actor_has_shadow (self);
-  appears_focused = meta_window_appears_focused (self->window);
+  appears_focused = meta_window_appears_focused (priv->window);
 
   if (appears_focused)
     {
-      recompute_shadow = self->recompute_focused_shadow;
-      self->recompute_focused_shadow = FALSE;
-      shadow_location = &self->focused_shadow;
+      recompute_shadow = priv->recompute_focused_shadow;
+      priv->recompute_focused_shadow = FALSE;
+      shadow_location = &priv->focused_shadow;
     }
   else
     {
-      recompute_shadow = self->recompute_unfocused_shadow;
-      self->recompute_unfocused_shadow = FALSE;
-      shadow_location = &self->unfocused_shadow;
+      recompute_shadow = priv->recompute_unfocused_shadow;
+      priv->recompute_unfocused_shadow = FALSE;
+      shadow_location = &priv->unfocused_shadow;
     }
 
   if (!should_have_shadow || recompute_shadow)
@@ -1570,8 +1676,8 @@ check_needs_shadow (MetaWindowActor *self)
 
   if (*shadow_location == NULL && should_have_shadow)
     {
-      if (self->shadow_shape == NULL)
-        self->shadow_shape = meta_window_shape_new (self->shape_region);
+      if (priv->shadow_shape == NULL)
+        priv->shadow_shape = meta_window_shape_new (priv->shape_region);
 
       MetaShadowFactory *factory = meta_shadow_factory_get_default ();
       const char *shadow_class = meta_window_actor_get_shadow_class (self);
@@ -1579,7 +1685,7 @@ check_needs_shadow (MetaWindowActor *self)
 
       meta_window_actor_get_shape_bounds (self, &shape_bounds);
       *shadow_location = meta_shadow_factory_get_shadow (factory,
-                                                         self->shadow_shape,
+                                                         priv->shadow_shape,
                                                          shape_bounds.width, shape_bounds.height,
                                                          shadow_class, appears_focused);
     }
@@ -1592,8 +1698,11 @@ void
 meta_window_actor_process_x11_damage (MetaWindowActor    *self,
                                       XDamageNotifyEvent *event)
 {
-  if (self->surface)
-    meta_surface_actor_process_damage (self->surface,
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (priv->surface)
+    meta_surface_actor_process_damage (priv->surface,
                                        event->area.x,
                                        event->area.y,
                                        event->area.width,
@@ -1603,9 +1712,12 @@ meta_window_actor_process_x11_damage (MetaWindowActor    *self,
 void
 meta_window_actor_sync_visibility (MetaWindowActor *self)
 {
-  if (CLUTTER_ACTOR_IS_VISIBLE (self) != self->visible)
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (CLUTTER_ACTOR_IS_VISIBLE (self) != priv->visible)
     {
-      if (self->visible)
+      if (priv->visible)
         clutter_actor_show (CLUTTER_ACTOR (self));
       else
         clutter_actor_hide (CLUTTER_ACTOR (self));
@@ -1654,6 +1766,8 @@ build_and_scan_frame_mask (MetaWindowActor       *self,
                            cairo_rectangle_int_t *client_area,
                            cairo_region_t        *shape_region)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   ClutterBackend *backend = clutter_get_default_backend ();
   CoglContext *ctx = clutter_backend_get_cogl_context (backend);
   guchar *mask_data;
@@ -1664,7 +1778,7 @@ build_and_scan_frame_mask (MetaWindowActor       *self,
   cairo_t *cr;
   cairo_surface_t *surface;
 
-  stex = meta_surface_actor_get_texture (self->surface);
+  stex = meta_surface_actor_get_texture (priv->surface);
   g_return_if_fail (stex);
 
   meta_shaped_texture_set_mask_texture (stex, NULL);
@@ -1691,7 +1805,7 @@ build_and_scan_frame_mask (MetaWindowActor       *self,
   gdk_cairo_region (cr, shape_region);
   cairo_fill (cr);
 
-  if (self->window->frame != NULL)
+  if (priv->window->frame != NULL)
     {
       cairo_region_t *frame_paint_region, *scanned_region;
       cairo_rectangle_int_t rect = { 0, 0, tex_width, tex_height };
@@ -1703,7 +1817,7 @@ build_and_scan_frame_mask (MetaWindowActor       *self,
       gdk_cairo_region (cr, frame_paint_region);
       cairo_clip (cr);
 
-      meta_frame_get_mask (self->window->frame, cr);
+      meta_frame_get_mask (priv->window->frame, cr);
 
       cairo_surface_flush (surface);
       scanned_region = scan_visible_region (mask_data, stride, frame_paint_region);
@@ -1752,19 +1866,21 @@ build_and_scan_frame_mask (MetaWindowActor       *self,
 static void
 meta_window_actor_update_shape_region (MetaWindowActor *self)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   cairo_region_t *region = NULL;
   cairo_rectangle_int_t client_area;
 
-  meta_window_get_client_area_rect (self->window, &client_area);
+  meta_window_get_client_area_rect (priv->window, &client_area);
 
-  if (self->window->frame != NULL && self->window->shape_region != NULL)
+  if (priv->window->frame != NULL && priv->window->shape_region != NULL)
     {
-      region = cairo_region_copy (self->window->shape_region);
+      region = cairo_region_copy (priv->window->shape_region);
       cairo_region_translate (region, client_area.x, client_area.y);
     }
-  else if (self->window->shape_region != NULL)
+  else if (priv->window->shape_region != NULL)
     {
-      region = cairo_region_reference (self->window->shape_region);
+      region = cairo_region_reference (priv->window->shape_region);
     }
   else
     {
@@ -1774,13 +1890,13 @@ meta_window_actor_update_shape_region (MetaWindowActor *self)
       region = cairo_region_create_rectangle (&client_area);
     }
 
-  if ((self->window->shape_region != NULL) || (self->window->frame != NULL))
+  if ((priv->window->shape_region != NULL) || (priv->window->frame != NULL))
     build_and_scan_frame_mask (self, &client_area, region);
 
-  g_clear_pointer (&self->shape_region, cairo_region_destroy);
-  self->shape_region = region;
+  g_clear_pointer (&priv->shape_region, cairo_region_destroy);
+  priv->shape_region = region;
 
-  g_clear_pointer (&self->shadow_shape, meta_window_shape_unref);
+  g_clear_pointer (&priv->shadow_shape, meta_window_shape_unref);
 
   meta_window_actor_invalidate_shadow (self);
 }
@@ -1788,7 +1904,9 @@ meta_window_actor_update_shape_region (MetaWindowActor *self)
 static void
 meta_window_actor_update_input_region (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
   cairo_region_t *region;
 
   if (window->shape_region && window->input_region)
@@ -1803,21 +1921,23 @@ meta_window_actor_update_input_region (MetaWindowActor *self)
   else
     region = NULL;
 
-  meta_surface_actor_set_input_region (self->surface, region);
+  meta_surface_actor_set_input_region (priv->surface, region);
   cairo_region_destroy (region);
 }
 
 static void
 meta_window_actor_update_opaque_region (MetaWindowActor *self)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   cairo_region_t *opaque_region;
   gboolean argb32 = is_argb32 (self);
 
-  if (argb32 && self->window->opaque_region != NULL)
+  if (argb32 && priv->window->opaque_region != NULL)
     {
       cairo_rectangle_int_t client_area;
 
-      meta_window_get_client_area_rect (self->window, &client_area);
+      meta_window_get_client_area_rect (priv->window, &client_area);
 
       /* The opaque region is defined to be a part of the
        * window which ARGB32 will always paint with opaque
@@ -1829,50 +1949,59 @@ meta_window_actor_update_opaque_region (MetaWindowActor *self)
        * to be undefined, and considered a client bug. In mutter's
        * case, graphical glitches will occur.
        */
-      opaque_region = cairo_region_copy (self->window->opaque_region);
+      opaque_region = cairo_region_copy (priv->window->opaque_region);
       cairo_region_translate (opaque_region, client_area.x, client_area.y);
-      cairo_region_intersect (opaque_region, self->shape_region);
+      cairo_region_intersect (opaque_region, priv->shape_region);
     }
   else if (argb32)
     opaque_region = NULL;
   else
-    opaque_region = cairo_region_reference (self->shape_region);
+    opaque_region = cairo_region_reference (priv->shape_region);
 
-  meta_surface_actor_set_opaque_region (self->surface, opaque_region);
+  meta_surface_actor_set_opaque_region (priv->surface, opaque_region);
   cairo_region_destroy (opaque_region);
 }
 
 static void
 check_needs_reshape (MetaWindowActor *self)
 {
-  if (!self->needs_reshape)
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  if (!priv->needs_reshape)
     return;
 
   meta_window_actor_update_shape_region (self);
 
-  if (self->window->client_type == META_WINDOW_CLIENT_TYPE_X11)
+  if (priv->window->client_type == META_WINDOW_CLIENT_TYPE_X11)
     {
       meta_window_actor_update_input_region (self);
       meta_window_actor_update_opaque_region (self);
     }
 
-  self->needs_reshape = FALSE;
+  priv->needs_reshape = FALSE;
 }
 
 void
 meta_window_actor_update_shape (MetaWindowActor *self)
 {
-  self->needs_reshape = TRUE;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  priv->needs_reshape = TRUE;
 
   if (is_frozen (self))
     return;
 
-  clutter_actor_queue_redraw (CLUTTER_ACTOR (self->surface));
+  clutter_actor_queue_redraw (CLUTTER_ACTOR (priv->surface));
 }
 
 static void
 meta_window_actor_handle_updates (MetaWindowActor *self)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
   if (is_frozen (self))
     {
       /* The window is frozen due to a pending animation: we'll wait until
@@ -1880,12 +2009,12 @@ meta_window_actor_handle_updates (MetaWindowActor *self)
       return;
     }
 
-  if (meta_surface_actor_is_unredirected (self->surface))
+  if (meta_surface_actor_is_unredirected (priv->surface))
     return;
 
-  meta_surface_actor_pre_paint (self->surface);
+  meta_surface_actor_pre_paint (priv->surface);
 
-  if (!meta_surface_actor_is_visible (self->surface))
+  if (!meta_surface_actor_is_visible (priv->surface))
     return;
 
   check_needs_reshape (self);
@@ -1906,17 +2035,19 @@ meta_window_actor_pre_paint (MetaWindowActor *self)
 static void
 do_send_frame_drawn (MetaWindowActor *self, FrameData *frame)
 {
-  MetaDisplay *display = meta_window_get_display (self->window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaDisplay *display = meta_window_get_display (priv->window);
   Display *xdisplay = meta_x11_display_get_xdisplay (display->x11_display);
 
   XClientMessageEvent ev = { 0, };
 
   frame->frame_drawn_time = meta_compositor_monotonic_time_to_server_time (display,
                                                                            g_get_monotonic_time ());
-  self->frame_drawn_time = frame->frame_drawn_time;
+  priv->frame_drawn_time = frame->frame_drawn_time;
 
   ev.type = ClientMessage;
-  ev.window = meta_window_get_xwindow (self->window);
+  ev.window = meta_window_get_xwindow (priv->window);
   ev.message_type = display->x11_display->atom__NET_WM_FRAME_DRAWN;
   ev.format = 32;
   ev.data.l[0] = frame->sync_request_serial & G_GUINT64_CONSTANT(0xffffffff);
@@ -1933,7 +2064,10 @@ do_send_frame_drawn (MetaWindowActor *self, FrameData *frame)
 void
 meta_window_actor_post_paint (MetaWindowActor *self)
 {
-  self->repaint_scheduled = FALSE;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  priv->repaint_scheduled = FALSE;
 
   if (meta_window_actor_is_destroyed (self))
     return;
@@ -1942,12 +2076,12 @@ meta_window_actor_post_paint (MetaWindowActor *self)
    * it is obscured, we should wait until timer expiration before
    * sending _NET_WM_FRAME_* messages.
    */
-  if (self->send_frame_messages_timer == 0 &&
-      self->needs_frame_drawn)
+  if (priv->send_frame_messages_timer == 0 &&
+      priv->needs_frame_drawn)
     {
       GList *l;
 
-      for (l = self->frames; l; l = l->next)
+      for (l = priv->frames; l; l = l->next)
         {
           FrameData *frame = l->data;
 
@@ -1955,12 +2089,12 @@ meta_window_actor_post_paint (MetaWindowActor *self)
             do_send_frame_drawn (self, frame);
         }
 
-      self->needs_frame_drawn = FALSE;
+      priv->needs_frame_drawn = FALSE;
     }
 
-  if (self->first_frame_state == DRAWING_FIRST_FRAME)
+  if (priv->first_frame_state == DRAWING_FIRST_FRAME)
     {
-      self->first_frame_state = EMITTED_FIRST_FRAME;
+      priv->first_frame_state = EMITTED_FIRST_FRAME;
       g_signal_emit (self, signals[FIRST_FRAME], 0);
     }
 }
@@ -1971,13 +2105,15 @@ do_send_frame_timings (MetaWindowActor  *self,
                        gint             refresh_interval,
                        gint64           presentation_time)
 {
-  MetaDisplay *display = meta_window_get_display (self->window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaDisplay *display = meta_window_get_display (priv->window);
   Display *xdisplay = meta_x11_display_get_xdisplay (display->x11_display);
 
   XClientMessageEvent ev = { 0, };
 
   ev.type = ClientMessage;
-  ev.window = meta_window_get_xwindow (self->window);
+  ev.window = meta_window_get_xwindow (priv->window);
   ev.message_type = display->x11_display->atom__NET_WM_FRAME_TIMINGS;
   ev.format = 32;
   ev.data.l[0] = frame->sync_request_serial & G_GUINT64_CONSTANT(0xffffffff);
@@ -2028,12 +2164,14 @@ meta_window_actor_frame_complete (MetaWindowActor  *self,
                                   ClutterFrameInfo *frame_info,
                                   gint64            presentation_time)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
   GList *l;
 
   if (meta_window_actor_is_destroyed (self))
     return;
 
-  for (l = self->frames; l;)
+  for (l = priv->frames; l;)
     {
       GList *l_next = l->next;
       FrameData *frame = l->data;
@@ -2043,12 +2181,12 @@ meta_window_actor_frame_complete (MetaWindowActor  *self,
         {
           if (G_UNLIKELY (frame->frame_drawn_time == 0))
             g_warning ("%s: Frame has assigned frame counter but no frame drawn time",
-                       self->window->desc);
+                       priv->window->desc);
           if (G_UNLIKELY (frame->frame_counter < frame_counter))
             g_warning ("%s: frame_complete callback never occurred for frame %" G_GINT64_FORMAT,
-                       self->window->desc, frame->frame_counter);
+                       priv->window->desc, frame->frame_counter);
 
-          self->frames = g_list_delete_link (self->frames, l);
+          priv->frames = g_list_delete_link (priv->frames, l);
           send_frame_timings (self, frame, frame_info, presentation_time);
           frame_data_free (frame);
         }
@@ -2060,8 +2198,11 @@ meta_window_actor_frame_complete (MetaWindowActor  *self,
 void
 meta_window_actor_invalidate_shadow (MetaWindowActor *self)
 {
-  self->recompute_focused_shadow = TRUE;
-  self->recompute_unfocused_shadow = TRUE;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
+  priv->recompute_focused_shadow = TRUE;
+  priv->recompute_unfocused_shadow = TRUE;
 
   if (is_frozen (self))
     return;
@@ -2072,21 +2213,26 @@ meta_window_actor_invalidate_shadow (MetaWindowActor *self)
 void
 meta_window_actor_update_opacity (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
 
-  if (self->surface)
-    clutter_actor_set_opacity (CLUTTER_ACTOR (self->surface), window->opacity);
+  if (priv->surface)
+    clutter_actor_set_opacity (CLUTTER_ACTOR (priv->surface), window->opacity);
 }
 
 static void
 meta_window_actor_set_updates_frozen (MetaWindowActor *self,
                                       gboolean         updates_frozen)
 {
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+
   updates_frozen = updates_frozen != FALSE;
 
-  if (self->updates_frozen != updates_frozen)
+  if (priv->updates_frozen != updates_frozen)
     {
-      self->updates_frozen = updates_frozen;
+      priv->updates_frozen = updates_frozen;
       if (updates_frozen)
         meta_window_actor_freeze (self);
       else
@@ -2097,7 +2243,9 @@ meta_window_actor_set_updates_frozen (MetaWindowActor *self,
 void
 meta_window_actor_sync_updates_frozen (MetaWindowActor *self)
 {
-  MetaWindow *window = self->window;
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (self);
+  MetaWindow *window = priv->window;
 
   meta_window_actor_set_updates_frozen (self, meta_window_updates_are_frozen (window));
 }
@@ -2127,16 +2275,18 @@ meta_window_actor_get_frame_bounds (MetaScreenCastWindow *screen_cast_window,
                                     MetaRectangle        *bounds)
 {
   MetaWindowActor *window_actor = META_WINDOW_ACTOR (screen_cast_window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (window_actor);
   MetaWindow *window;
   MetaShapedTexture *stex;
   MetaRectangle buffer_rect;
   MetaRectangle frame_rect;
   double scale_x, scale_y;
 
-  stex = meta_surface_actor_get_texture (window_actor->surface);
+  stex = meta_surface_actor_get_texture (priv->surface);
   clutter_actor_get_scale (CLUTTER_ACTOR (stex), &scale_x, &scale_y);
 
-  window = window_actor->window;
+  window = priv->window;
   meta_window_get_buffer_rect (window, &buffer_rect);
   meta_window_get_frame_rect (window, &frame_rect);
 
@@ -2155,6 +2305,8 @@ meta_window_actor_transform_relative_position (MetaScreenCastWindow *screen_cast
 
 {
   MetaWindowActor *window_actor = META_WINDOW_ACTOR (screen_cast_window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (window_actor);
   MetaShapedTexture *stex;
   MetaRectangle bounds;
   ClutterVertex v1 = { 0.f, }, v2 = { 0.f, };
@@ -2168,7 +2320,7 @@ meta_window_actor_transform_relative_position (MetaScreenCastWindow *screen_cast
                 bounds.y,
                 bounds.y + bounds.height);
 
-  stex = meta_surface_actor_get_texture (window_actor->surface);
+  stex = meta_surface_actor_get_texture (priv->surface);
   clutter_actor_apply_transform_to_point (CLUTTER_ACTOR (stex), &v1, &v2);
 
   *x_out = (double) v2.x;
@@ -2181,6 +2333,8 @@ meta_window_actor_capture_into (MetaScreenCastWindow *screen_cast_window,
                                 uint8_t              *data)
 {
   MetaWindowActor *window_actor = META_WINDOW_ACTOR (screen_cast_window);
+  MetaWindowActorPrivate *priv =
+    meta_window_actor_get_instance_private (window_actor);
   cairo_surface_t *image;
   MetaRectangle clip_rect;
   uint8_t *cr_data;
@@ -2191,7 +2345,7 @@ meta_window_actor_capture_into (MetaScreenCastWindow *screen_cast_window,
     return;
 
   clip_rect = *bounds;
-  image = meta_surface_actor_get_image (window_actor->surface, &clip_rect);
+  image = meta_surface_actor_get_image (priv->surface, &clip_rect);
   cr_data = cairo_image_surface_get_data (image);
   cr_stride = cairo_image_surface_get_stride (image);
 
diff --git a/src/meta/meta-window-actor.h b/src/meta/meta-window-actor.h
index c1bc02b68..0b1f79d45 100644
--- a/src/meta/meta-window-actor.h
+++ b/src/meta/meta-window-actor.h
@@ -29,11 +29,10 @@
 #include "meta/compositor.h"
 
 #define META_TYPE_WINDOW_ACTOR (meta_window_actor_get_type ())
-G_DECLARE_FINAL_TYPE (MetaWindowActor,
-                      meta_window_actor,
-                      META, WINDOW_ACTOR,
-                      ClutterActor)
-
+G_DECLARE_DERIVABLE_TYPE (MetaWindowActor,
+                          meta_window_actor,
+                          META, WINDOW_ACTOR,
+                          ClutterActor)
 
 Window             meta_window_actor_get_x_window         (MetaWindowActor *self);
 MetaWindow *       meta_window_actor_get_meta_window      (MetaWindowActor *self);