<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
    <mx:Script>
        <![CDATA[
            private function labelFunction(item:Object):String
            {
                return "Changed";
            }
        ]]>
    </mx:Script>
    
    <mx:ArrayCollection id="flat"   source="{['one','two','three']}"/>
    <mx:ArrayCollection id="fields" source="{[{label:'one'},{label:'two'},{label:'three'}]}"/>
    
    <mx:HBox>
        <mx:List        labelFunction="labelFunction" dataProvider="{fields}"/>
        <mx:ButtonBar   labelFunction="labelFunction" dataProvider="{fields}" direction="vertical"/>
        
        <mx:Spacer width="50"/>
        
        <mx:List        labelFunction="labelFunction" dataProvider="{flat}"/>
        <mx:ButtonBar   labelFunction="labelFunction" dataProvider="{flat}" direction="vertical"/>
    </mx:HBox>
</mx:Application>