      *  @playerversion AIR 1.5
      *  @productversion Flex 4
      */
-    protected function viewportVerticalScrollPositionChangeHandler(event:PropertyChangeEvent):void
+    mx_internal function viewportVerticalScrollPositionChangeHandler(event:PropertyChangeEvent):void
     {
     }   
     

    *  @playerversion AIR 1.5
    *  @productversion Flex 4
    */
    protected function viewportContentWidthChangeHandler(event:PropertyChangeEvent):void
    {
    }
    
    /**
     *  Called when the viewport's <code>contentHeight</code> value changes. Does nothing by default.
     *  
     *  @langversion 3.0

    *  @playerversion AIR 1.5
    *  @productversion Flex 4
    */
    mx_internal function viewportResizeHandler(event:ResizeEvent):void
    {
    }
    
   /**
    *  @private
    *  Called when the viewport's <code>contentWidth</code> value changes. Does nothing by default.
    *  
    *  @langversion 3.0
