+DALI_CORE_API VisibilityChangedSignalType& VisibilityChangedSignal( Actor actor );
+
+/**
+ * Calculates screen position and size.
+ *
+ * @return pair of two values, position of top-left corner on screen and size respectively.
+ */
+DALI_CORE_API Rect<> CalculateScreenExtents( Actor actor );
+
+
+
+typedef Signal< void (Actor) > ChildChangedSignalType; ///< Called when the actor has a child added or removed
+
+/**
+ * @brief This signal is emitted when a child is added to this actor.
+ *
+ * A callback of the following type may be connected:
+ * @code
+ * void MyCallbackName( Actor child );
+ * @endcode
+ * child: The child that has been added.
+ *
+ * @note Use this signal with caution. Changing the parent of the actor
+ * within this callback is possible, but DALi will prevent further signals
+ * being sent.
+ *
+ * @return The signal to connect to
+ * @pre The Actor has been initialized
+ */
+DALI_CORE_API ChildChangedSignalType& ChildAddedSignal( Actor actor );
+
+/**
+ * @brief This signal is emitted when a child is removed from this actor.
+ *
+ * A callback of the following type may be connected:
+ * @code
+ * void MyCallbackName( Actor child );
+ * @endcode
+ * child: The child that has been removed.
+ *
+ * @note Use this signal with caution. Changing the parent of the actor
+ * within this callback is possible, but DALi will prevent further signals
+ * being sent.
+ *
+ * @note If the child actor is moved from one actor to another, then
+ * this signal will be emitted followed immediately by an
+ * ChildAddedSignal() on the new parent.
+ *
+ * @return The signal to connect to
+ * @pre The Actor has been initialized
+ */
+DALI_CORE_API ChildChangedSignalType& ChildRemovedSignal( Actor actor );
+
+
+typedef Signal< void (Actor) > ChildOrderChangedSignalType; ///< Used when the actor's children have changed order
+
+/**
+ * @brief This signal is emitted when an actor's children change their sibling order
+ *
+ * A callback of the following type may be connected:
+ * @code
+ * void MyCallbackName( Actor parent );
+ * @endcode
+ * parent The parent actor of the moved children
+ *
+ * @return The signal to connect to
+ * @pre The Actor has been initialized
+ */
+DALI_CORE_API ChildOrderChangedSignalType& ChildOrderChangedSignal( Actor actor );
+
+