渐变显示的对话框

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
 
    <mx:Style>
        global {
            modalTransparencyBlur: 0;
            modalTransparency: 0.8;
            modalTransparencyColor: black;
            modalTransparencyDuration: 500;
        }
    </mx:Style>
 
    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;
            import mx.managers.PopUpManager;
 
            private function showAlert():void {
                Alert.show("hello", "world");
            }
 
            private function showContactForm():void {
                var contactForm:ContactForm = new ContactForm();
                PopUpManager.addPopUp(contactForm, this, true);
            }
        ]]>
    </mx:Script>
 
    <mx:ApplicationControlBar dock="true">
        <mx:Button label="Alert" click="showAlert();" />
        <mx:Button label="ContactForm" click="showContactForm();" />
    </mx:ApplicationControlBar>
 
</mx:Application>