flex 桌面程序运行时居中显示

<mx:transitions>

<mx:Transition id="myTransition1" fromState="*" toState="main">  

                <mx:Sequence id="shake3" targets="{[top,cvs,left]}" duration="200" repeatCount="1">

       <mx:Move yBy="{this.height}"/>

       <mx:Move yBy="-5"/>

   </mx:Sequence>

    </mx:Transition>

 

    <mx:Transition id="myTransition2" fromState="*" toState="*"> 

                <mx:Sequence id="shake4" target="{panel}" duration="200" repeatCount="1">

       <mx:Move yBy="{this.height}"/>

       <mx:Move yBy="-5"/>

     </mx:Sequence>

    </mx:Transition>

</mx:transitions>