Flex Datagrid 内容超出 column 宽度显示 tooltip

package 
{
	import mx.controls.dataGridClasses.DataGridItemRenderer;

	public class TruncateText extends DataGridItemRenderer 
	{
		private var textTruncated:Boolean = false;
		private var originalText:String;

		public function TruncateText()
		{
			super();
		}

		override public function set text(value:String):void
		{
			super.text = value;
			originalText = value;
			textTruncated = truncateToFit();
		}

		override public function validateProperties():void
		{
			super.validateProperties();
			this.wordWrap=false;
			this.setStyle("paddingTop",0);
			this.setStyle("paddingBottom",0);
			this.setStyle("paddingLeft",0);
			this.setStyle("paddingRight",0);
			toolTip = textTruncated ? originalText : null;
		}
	}
}