<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/04/10/removing-the-track-skin-from-a-list-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Style>
        .tracklessScrollBar {
            trackSkin: ClassReference(null);
        }
    </mx:Style>

    <mx:Script>
        <![CDATA[
            import mx.events.ItemClickEvent;

            private function toggleButtonBar_itemClick(evt:ItemClickEvent):void {
                list.setStyle("verticalScrollBarStyleName", evt.item.data);
            }
        ]]>
    </mx:Script>

    <mx:Array id="arr">
        <mx:Object label="One" />
        <mx:Object label="Two" />
        <mx:Object label="Three" />
        <mx:Object label="Four" />
        <mx:Object label="Five" />
        <mx:Object label="Six" />
        <mx:Object label="Seven" />
        <mx:Object label="Eight" />
        <mx:Object label="Nine" />
        <mx:Object label="Ten" />
    </mx:Array>

    <mx:Array id="dp">
        <mx:Object label="default (undefined)"
                data="{undefined}" />
        <mx:Object label="tracklessScrollBar"
                data="tracklessScrollBar" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:ToggleButtonBar id="toggleButtonBar"
                dataProvider="{dp}"
                itemClick="toggleButtonBar_itemClick(event);" />
    </mx:ApplicationControlBar>

    <mx:List id="list"
            dataProvider="{arr}"
            rowCount="6"
            width="100" />

</mx:Application>