flex用图片制作按钮

<?xml version="1.0"?>
<!-- embed\ButtonIconCSS.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
            <mx:Style>  
                .myCustomButton {
                       overSkin:Embed(source="overIconImage.gif");
                       upSkin:Embed(source="upIconImage.gif");
                       downSkin:Embed(source="downIconImage.gif");
                }
            </mx:Style>
            <mx:Button label="Icon Button Style Def" styleName="myCustomButton"/>
</mx:Application>