Setting the background color and background alpha on a Flex PopUpButton control’s pop up menu

The following example shows how you can change the background color and alpha of a PopUpButton control’s pop up menu in Flex by setting the popUpStyleName, backgroundAlpha, and backgroundColor styles.

<?xml version="1.0"?>
<!-- http://blog.flexexamples.com/2008/01/17/setting-the-background-color-and-background-alpha-on-a-flex-popupbutton-controls-pop-up-menu/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="top"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.controls.Menu;
            import mx.events.MenuEvent;

            [Bindable]
            private var menu:Menu;

            private function initMenu():void {
                menu = new Menu();
                menu.dataProvider = arr;
                menu.setStyle("themeColor", "black");
            }
        ]]>
    </mx:Script>

    <mx:Array id="arr">
        <mx:Object label="Button" />
        <mx:Object label="ButtonBar" />
        <mx:Object label="ColorPicker" />
        <mx:Object label="ComboBox" />
    </mx:Array>

    <mx:Style>
        .myPop {
            backgroundAlpha: 0.7;
            backgroundColor: black;
            borderStyle: none;
            color: white;
        }
    </mx:Style>

    <mx:ApplicationControlBar dock="true">
        <mx:PopUpButton id="popUpButton"
                label="Select a control"
                popUp="{menu}"
                popUpStyleName="myPop"
                preinitialize="initMenu();" />
    </mx:ApplicationControlBar>

    <mx:VBox backgroundColor="haloSilver"
            width="100%"
            height="100%" />

</mx:Application>