 
         opaqueBackground = 0xFFFFFF;
 
-        _mask = new Sprite();
+        _mask = new Shape();
         rawChildren.addChild(_mask);
         this.mask = _mask;
 

    protected var _maxHeight :int;

    protected var _box :Sprite;
    protected var _mask :Sprite;

    protected var _scale :Number;



import flash.display.DisplayObject;
import flash.display.Graphics;
import flash.display.Shape;
import flash.display.Sprite;

import flash.events.Event;
