Flex 4中设置ToolTip文本字体的大小

<?xml version="1.0" encoding="utf-8"?><s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"    xmlns:s="library://ns.adobe.com/flex/spark"    xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"   creationComplete="application1_creationCompleteHandler(event)"><fx:Declarations><!-- 将非可视元素（例如服务、值对象）放在此处 --><mx:Rotate id="rotate" /></fx:Declarations><fx:Script><![CDATA[import mx.events.FlexEvent;import mx.managers.ToolTipManager;protected function application1_creationCompleteHandler(event:FlexEvent):void{// TODO Auto-generated method stubToolTipManager.showEffect = rotate;StyleManager.getStyleManager(null).getStyleDeclaration('mx.controls.ToolTip').setStyle('fontSize',18);}]]></fx:Script><s:Button y="100" label="test tooltip" toolTip="my tooltip showed." /></s:Application>