使用PopUpManager 和TitleWindow 类：

代码：

<?xml version="1.0" encoding="utf-8"?>

<!-- http://blog.flexexamples.com/2007/08/20/creating-custom-dialog-boxes-using-the-popupmanager-and-titlewindow-classes/ -->

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"

        layout="vertical"

        verticalAlign="middle"

        backgroundColor="white"

        creationComplete="init()">


    <mx:Script>

        <![CDATA[

            import mx.controls.Label;

            import mx.events.CloseEvent;

            import mx.containers.TitleWindow;

            import mx.managers.PopUpManager;


            private var titleWindow:TitleWindow;


            private function init():void {

                var label:Label = new Label();

                label.text = "Hello world";


                titleWindow = new TitleWindow();

                titleWindow.title = "Custom title";

                titleWindow.showCloseButton = true;

                titleWindow.width = 240;

                titleWindow.height = 180;

                titleWindow.addEventListener(CloseEvent.CLOSE, titleWindow_close);

                titleWindow.addChild(label);


                PopUpManager.addPopUp(titleWindow, this, true);

                PopUpManager.centerPopUp(titleWindow);

            }


            private function titleWindow_close(evt:CloseEvent):void {

                PopUpManager.removePopUp(titleWindow);

            }

        ]]>

    </mx:Script>


    <mx:Button label="Launch TitleWindow" click="init()" />


</mx:Application>