actor: Add a method for querying key focus

A simple convenience method on Clutter.Actor for checking whether
it has key focus assigned on the Stage to which it belongs.

clutter/clutter-actor.c

@@ -11643,3 +11643,27 @@ clutter_actor_clear_effects (ClutterActor *self)
 
   _clutter_meta_group_clear_metas (self->priv->effects);
 }
+
+/**
+ * clutter_actor_has_key_focus:
+ * @self: a #ClutterActor
+ *
+ * Checks whether @self is the #ClutterActor that has key focus
+ *
+ * Return value: %TRUE if the actor has key focus, and %FALSE otherwise
+ *
+ * Since: 1.4
+ */
+gboolean
+clutter_actor_has_key_focus (ClutterActor *self)
+{
+  ClutterActor *stage;
+
+  g_return_val_if_fail (CLUTTER_IS_ACTOR (self), FALSE);
+
+  stage = clutter_actor_get_stage_internal (self);
+  if (stage == NULL)
+    return FALSE;
+
+  return clutter_stage_get_key_focus (CLUTTER_STAGE (stage)) == self;
+}

clutter/clutter-actor.h

@@ -585,6 +585,8 @@ gboolean             clutter_actor_has_allocation     (ClutterActor         *sel
 
 AtkObject *          clutter_actor_get_accessible     (ClutterActor         *self);
 
+gboolean             clutter_actor_has_key_focus      (ClutterActor         *self);
+
 G_END_DECLS
 
 #endif /* __CLUTTER_ACTOR_H__ */

doc/reference/clutter/clutter-sections.txt

@@ -403,6 +403,7 @@ clutter_actor_set_shader_param_float
 clutter_actor_set_shader_param_int
 
 <SUBSECTION>
+clutter_actor_has_key_focus
 clutter_actor_grab_key_focus
 clutter_actor_get_pango_context
 clutter_actor_create_pango_context