<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/10/04/setting-the-tab-width-on-a-tabbar-control-in-flex/ -->
<mx:Application name="TabBar_tabWidth_test"
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Array id="arr">
        <mx:Object label="Red" />
        <mx:Object label="Orange" />
        <mx:Object label="Yellow" />
        <mx:Object label="Green" />
        <mx:Object label="Blue" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="tabWidth:">
                <mx:HSlider id="slider"
                        minimum="40"
                        maximum="120"
                        value="100"
                        snapInterval="1"
                        tickInterval="10"
                        liveDragging="true" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:TabBar id="tabBar"
            dataProvider="{arr}"
            tabWidth="{slider.value}" />

</mx:Application>