flex tooltip css

<?xml version="1.0"?>
<!-- tooltips/ToolTipStyleManager.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" creationComplete="setToolTipStyle()">

  <mx:Script><![CDATA[
     import mx.styles.StyleManager;
     private function setToolTipStyle():void {
        StyleManager.getStyleDeclaration("ToolTip").setStyle("fontStyle","italic");
        StyleManager.getStyleDeclaration("ToolTip").setStyle("fontSize","19");
        StyleManager.getStyleDeclaration("ToolTip").setStyle("fontFamily","Arial");
        StyleManager.getStyleDeclaration("ToolTip").setStyle("color","#FF6699");
        StyleManager.getStyleDeclaration("ToolTip").setStyle("backgroundColor","#33CC99");
     }
]]></mx:Script>

  <mx:Button id="b1" label="Click Me" toolTip="This Button does nothing."/>

</mx:Application>