Self Closing Alert in Flex

How to create self closing alert box in adobe flex:
Following are the application of Auto closing alert box in adobe flex
<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/04/08/creating-a-self-closing-alert-control-in-flex/ -->
<mx:Application name="Alert_PopUpManager_removePopUp_test"
xmlns:mx="http://www.adobe.com/2006/mxml"
backgroundColor="white"
initialize="init();">

<mx:Script>
<![CDATA[
import mx.controls.Alert;
import mx.events.CloseEvent;
import mx.managers.PopUpManager;

private var alrt:Alert;
private var alrtTimer:Timer;

private function init():void {
alrtTimer = new Timer(5000, 1);
alrtTimer.addEventListener(TimerEvent.TIMER_COMPLETE, removeAlert);
}

private function showAlert():void {
alrt = Alert.show("I'm an Alert control and I will close in 5 seconds unless closed by a user.", "Self closing Alert", Alert.OK, this, alrt_close);
alrtTimer.reset();
alrtTimer.start();
}

private function alrt_close(evt:CloseEvent):void {
alrtTimer.stop();
lbl.text = "Closed by user.";
}

private function removeAlert(evt:TimerEvent):void {
PopUpManager.removePopUp(alrt);
lbl.text = "Removed by application.";
}
]]>
</mx:Script>

<mx:Button label="Show Alert" click="showAlert();" />
<mx:Label id="lbl" />

</mx:Application>