flex TitleWindow 关闭按钮样式 closeButton

flex3的mx.containers.TitleWindow的示例
网址：http://blog.flexexamples.com/2007/12/31/changing-the-close-button-skin-on-a-flex-titlewindow-container/

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
		layout="vertical"
		verticalAlign="middle"
		backgroundColor="white">

	<mx:Style>
		TitleWindow {
			closeButtonSkin: Embed("cancel.png");
			/* Set values from defaults.css to null. */
			closeButtonDisabledSkin: ClassReference(null);
			closeButtonDownSkin: ClassReference(null);
			closeButtonOverSkin: ClassReference(null);
			closeButtonUpSkin: ClassReference(null);
		}
	</mx:Style>

	<mx:TitleWindow id="titleWindow"
			title="TitleWindow"
			status="status message"
			showCloseButton="true"
			width="100%"
			height="100%" />

</mx:Application>

flex4 spark.components.TitleWindow的关闭按钮的样式自定义
网址：http://blog.flexexamples.com/2010/04/04/changing-the-close-button-skin-on-the-spark-titlewindow-container-in-flex-4/
使用该方法后，button可以响应鼠标的区域可能很小。为button下面的组件指定alpha值后，button的整个区域都可以响应鼠标事件了。