PopUpAnchor control in Flex 4

<?xml version="1.0" encoding="utf-8"?><!-- http://blog.flexexamples.com/2010/01/20/setting-the-pop-up-position-on-a-spark-popupanchor-control-in-flex-4/ --><s:Application name="Spark_PopUpAnchor_popUpPosition_test"        xmlns:fx="http://ns.adobe.com/mxml/2009"        xmlns:s="library://ns.adobe.com/flex/spark"        xmlns:mx="library://ns.adobe.com/flex/mx">    <s:controlBarContent>        <mx:Form>            <mx:FormItem label="popUpPosition:">                <s:ButtonBar id="ddl"                        requireSelection="true"                        click="ddl_changeHandler(event);"                        >                    <s:dataProvider>                        <s:ArrayList>                            <s:source>                                <fx:String>{PopUpPosition.ABOVE}</fx:String>                                <fx:String>{PopUpPosition.BELOW}</fx:String>                                <fx:String>{PopUpPosition.CENTER}</fx:String>                                <fx:String>{PopUpPosition.LEFT}</fx:String>                                <fx:String>{PopUpPosition.RIGHT}</fx:String>                                <fx:String>{PopUpPosition.TOP_LEFT}</fx:String>                            </s:source>                        </s:ArrayList>                    </s:dataProvider>                </s:ButtonBar>            </mx:FormItem>        </mx:Form>    </s:controlBarContent>     <fx:Script>        <![CDATA[            import mx.events.CloseEvent;            import spark.components.PopUpPosition;            import spark.events.IndexChangeEvent;            import spark.events.TitleWindowBoundsEvent;             protected function btn_clickHandler(evt:MouseEvent):void {                popAnc.displayPopUp = true;            }             protected function ttlWndw_closeHandler(evt:CloseEvent):void {                popAnc.displayPopUp = false;            }             protected function ttlWndw_windowMovingHandler(evt:TitleWindowBoundsEvent):void {                evt.stopImmediatePropagation();                evt.preventDefault();            }             protected function ddl_changeHandler(evt:Event):void {                if (!popAnc.displayPopUp) {                    popAnc.displayPopUp = true;                }            }        ]]>    </fx:Script>     <s:Group horizontalCenter="0" verticalCenter="0">        <s:Button id="btn"                label="Open PopUp"                chromeColor="haloBlue"                click="btn_clickHandler(event);" />        <s:PopUpAnchor id="popAnc"                popUpPosition="{ddl.selectedItem}"                width="{btn.width}" height="{btn.height}">            <s:TitleWindow id="ttlWndw"                    title="{ddl.selectedItem}"                    backgroundAlpha="0.3"                    backgroundColor="black"                    close="ttlWndw_closeHandler(event);"                    windowMoving="ttlWndw_windowMovingHandler(event);">                <mx:Form>                    <mx:FormItem label="Username:">                        <s:TextInput />                    </mx:FormItem>                    <mx:FormItem label="Password:">                        <s:TextInput displayAsPassword="true" />                    </mx:FormItem>                </mx:Form>            </s:TitleWindow>        </s:PopUpAnchor>    </s:Group> </s:Application>

转载：http://blog.flexexamples.com/2010/01/20/setting-the-pop-up-position-on-a-spark-popupanchor-control-in-flex-4/