title: flex tabnavigator skin flicker
body: <p>I am try to skin my tabnavigator with PNG byextend with TabSkin.as and SelectedTabSkin.as, however, when I tried to mouseover the tab buttons, it will caused a flicker into black and load the tab image which I define. What can I do to avoid flicker?</p>
  
  <p>TabSkin.as same as SelectedTabSkin.as but different image</p>
  
  <pre><code>package {
   import mx.controls.Image;
  
   public class TabSkin extends Image {
      public function TabSkin():void {
          super();
      }
  
  
      override protected  function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void {
          this.source = "asset/bb.png";
          this.styleName = "tab";
          super.updateDisplayList(unscaledWidth, unscaledHeight);
      }
  
  }
  </code></pre>
  
  <p>}</p>
  
  <p>Tab.MXML</p>
  
  <pre><code>    TabNavigator {
         tabHeight: 39;
         tab-width: 108;
         tabOffset: 1;
         tabStyleName: "tab";
      }
  
      .tab {
           fillColors: #000000, #000000;
           up-skin: ClassReference("TabSkin");
           down-skin: ClassReference("TabSkin");
           over-skin: ClassReference("TabSkin");
  
      selected-up-skin: ClassReference("SelectedTabSkin");
      selected-down-skin: ClassReference("SelectedTabSkin");
      selected-over-skin: ClassReference("SelectedTabSkin");
      }
  
      .selectedTab {
           font-weight: bold;
           corner-radius: 0;
      }
  
  &lt;mx:TabNavigator x="223" y="82" width="100%" height="100%" id="tab2"/&gt;
  </code></pre>