This did it: main MXML all script:
import mx.managers.PopUpManager; import mx.controls.Alert; public function show(messageItem:String): void { var alertInstance:alertPopupDialog = alertPopupDialog(PopUpManager.createPopUp(this, alertPopupDialog, true)); //instantiate and show the title window PopUpManager.centerPopUp(alertInstance); alertInstance.messageString = messageItem; } titleWindow MXML component <?xml version="1.0" encoding="utf-8"?> <mx:TitleWindow xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="596" height="134" title="Attention:" titleIcon="@Embed(source='/images/alarmicon.png')" styleName="alertStyle" creationComplete="setTimer();"> <mx:Style> .alertStyle { font-family: Verdana; flashType: true; font-weight: normal; color: #000000; font-size: 18pt; background-color: #FF9999; border-color: #FF9999; roundedBottomCorners: true; cornerRadius: 15; borderStyle: solid; } </mx:Style> <mx:Script> <![CDATA[ import flash.utils.Timer; import mx.managers.PopUpManager; public var timer:Timer; [Bindable] public var messageString:String; private function setTimer():void { timer = new Timer(5000, 1); timer.addEventListener(TimerEvent.TIMER, onTimer); if (timer.running) { timer.stop(); } timer.start(); } public function onTimer(event : TimerEvent):void { timer.removeEventListener(TimerEvent.TIMER, onTimer); PopUpManager.removePopUp(this); } ]]> </mx:Script> <mx:Label x="10" y="30" textAlign="left" fontSize="18" id="alertMessage" text="{messageString}"/> </mx:TitleWindow>