VBox c cornerRadius и чайлды.

[GBee]

<?xml version="1.0" encoding="utf-8"?>
<!-- Simple example to demonstrate the Halo LinkButton control. -->
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/mx" creationComplete="cre()" backgroundColor="red" height="200" width="200">
    <fx:Style source="datagridskin.css"/>
 
    <fx:Script>
        <![CDATA[
            private function cre():void {
                qwe.setStyle("cornerRadius", 15);
                qwe.setStyle("backgroundColor", "blue");
            }    
        ]]>
    </fx:Script>    
    <mx:VBox width="150" height="150" id="qwe" mask="{qweMask}">
        <mx:LinkButton label="32121312"/>
        <mx:LinkButton label="sdfsd"/>
        <mx:LinkButton label="sdfsd"/>
        <mx:LinkButton label="sdfsd"/>
    </mx:VBox>
<mx:Canvas width="150" height="150" id="qweMask" cornerRadius="15" backgroundColor="#990000" />
</s:Application>

Примерно так, только у апликейшена лейаут абсолютный должен быть