<!-- http://blog.flexexamples.com/2008/02/26/displaying-a-tree-control-as-a-pop-up-for-a-flex-popupbutton-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="vertical"
verticalAlign="middle"
backgroundColor="white">
<mx:Style>
Tree {
textAlign: left;
fontWeight: normal;
}
</mx:Style>
<mx:XML id="mlb" source="mlb.xml" />
<mx:ApplicationControlBar dock="true">
<mx:PopUpButton label="Please select a team">
<mx:popUp>
<mx:Tree id="tree"
dataProvider="{mlb}"
labelField="@label"
showRoot="false"
width="200"
rowCount="8" />
</mx:popUp>
</mx:PopUpButton>
</mx:ApplicationControlBar>
</mx:Application>