mustella/tests/DownloadProgressBar/SWFs/assets/SparkAlphaMain.mxml

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark"
    preloader="SparkAlphaProgressBar"
    width="300" height="250" >
    <s:layout>
        <s:VerticalLayout />
    </s:layout>
    <s:Button label="Test"/>
</s:Application>