<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/01/31/setting-the-corner-radius-on-a-flex-popupbutton-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
		layout="vertical"
		verticalAlign="top"
		backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Style>
        PopUpButton {
            popUpStyleName: myCustomPopUpStyleName;
        }

        .myCustomPopUpStyleName {
            fontWeight: normal;
            textAlign: left;
            leftIconGap: 0;
        }
    </mx:Style>

	<mx:Script>
		<![CDATA[
			import mx.controls.Menu;

			private function init():void {
				var menu:Menu = new Menu();
				menu.dataProvider = arr;
				popUpButton.popUp = menu;
			}

			private function resizePopUp():void {
				popUpButton.popUp.width = popUpButton.width;
			}
		]]>
	</mx:Script>

	<mx:Array id="arr">
		<mx:Object label="Alert" />
		<mx:Object label="Button" />
		<mx:Object label="ButtonBar" />
		<mx:Object type="separator" />
		<mx:Object label="CheckBox" />
		<mx:Object label="ColorPicker" />
		<mx:Object label="ComboBox" />
	</mx:Array>

	<mx:ApplicationControlBar dock="true">
		<mx:Form styleName="plain">
			<mx:FormItem label="cornerRadius:">
				<mx:HSlider id="slider"
						minimum="0"
						maximum="{popUpButton.height / 2}"
						value="0"
						liveDragging="true"
						snapInterval="1"
						tickInterval="1" />
			</mx:FormItem>
		</mx:Form>
	</mx:ApplicationControlBar>

	<mx:PopUpButton id="popUpButton"
			label="Please select an item..."
			cornerRadius="{slider.value}"
			arrowButtonWidth="{popUpButton.height}"
			openAlways="true"
			initialize="init();"
			creationComplete="resizePopUp();" />

</mx:Application>