设置下拉框文字过长用省略号显示，并设置tooltip

<?xml version="1.0" encoding="utf-8"?> 
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
        layout="vertical" 
        verticalAlign="top" 
        backgroundColor="white"> 
  
    <mx:ApplicationControlBar dock="true"> 
        <mx:Label text="width:" /> 
        <mx:HSlider id="slider" 
                minimum="50" 
                maximum="200" 
                value="80" 
                liveDragging="true" 
                labels="[50,200]" 
                tickInterval="50" 
                snapInterval="10" /> 
    </mx:ApplicationControlBar> 
  
    <mx:ComboBox id="comboBox" 
            width="{slider.value}" 
            itemRenderer="mx.controls.Label"> 
        <mx:dataProvider> 
            <mx:Array> 
                <mx:Object label="1234567890" /> 
                <mx:Object label="The quick brown fox" /> 
                <mx:Object label="Lorem ipsum" /> 
            </mx:Array> 
        </mx:dataProvider> 
    </mx:ComboBox> 
  
</mx:Application>