 import spark.effects.easing.IEaser;
 import spark.effects.easing.Linear;
 import spark.effects.easing.Sine;
+
+use namespace mx_internal;
 
 /**
  *  @copy spark.components.supportClasses.GroupBase#symbolColor

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

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