flex4 控制弹出窗口的拖动范围

不让其超出系统边界，侦听其move事件，不用改写组件。

?

代码：

var newWin:spark.components.TitleWindow=win as spark.components.TitleWindow;
				newWin.addEventListener(MoveEvent.MOVE,moveRhandler);
				PopUpManager.addPopUp(newWin,this,false);
				PopUpManager.centerPopUp(newWin );
					
			}
			
			private function moveRhandler(event:MoveEvent):void
			{
				var dx:Number=(event.currentTarget as spark.components.TitleWindow).x;
				var dy:Number=(event.currentTarget as spark.components.TitleWindow).y;
				var comp:spark.components.TitleWindow=event.currentTarget as spark.components.TitleWindow;
				if(dx<0)
					comp.x=0;
				if(dx>FlexGlobals.topLevelApplication.width-comp.width)
					comp.x=FlexGlobals.topLevelApplication.width-comp.width;
				if(dy<0)
					comp.y=0;
				if(dy>FlexGlobals.topLevelApplication.height-comp.height)
					comp.y=FlexGlobals.topLevelApplication.height-comp.height;
				
			}