flex中textarea事件

import flash.text.TextField;
import flash.events.TextEvent;
import flash.text.TextFieldAutoSize;


var txt:TextField = new TextField();
this.addChild(txt);

txt.htmlText = "<font color='#ff0000'><a href='event:关于本站'>关于本站</a></font> | <a href='event:广告服务'>广告服务</a>";
txt.autoSize = TextFieldAutoSize.LEFT;
txt.addEventListener(TextEvent.LINK,th)
function th($evt:TextEvent):void
{
        if($evt.text == "关于本站")
        {
                trace("关于本站");
        }
        else if($evt.text == "广告服务")
        {
                trace("广告服务");
        }
}