flex中datagrid当字体超出长度时显示标题完整字体

<?xml version="1.0" encoding="utf-8"?>
<!-- LabelExample.mxml -->
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" 
               viewSourceURL="srcview/index.html" creationComplete="init()">
    <s:layout>
        <s:VerticalLayout/>
    </s:layout>
    
    <fx:Declarations>
        <s:ArrayCollection id="MyFlexHero">
            <s:source>
                <fx:Array>
                    <fx:Object a="1" b="One.1" c="One.2" />
                    <fx:Object a="2" b="Two.1" c="Two.2" />
                    <fx:Object a="3" b="Three.1" c="Three.2" />
                    <fx:Object a="4" b="Four.1" c="Four.2" />
                    <fx:Object a="5" b="Five.1" c="Five.2" />
                    <fx:Object a="6" b="Six.1" c="Six.2" />
                    <fx:Object a="7" b="Seven.1" c="Seven.2" />
                    <fx:Object a="8" b="Eight.1" c="Eight.2" />
                    <fx:Object a="9" b="Nine.1" c="Nine.2" />
                    <fx:Object a="10" b="Ten.1" c="Ten.2" />
                    <fx:Object a="11" b="Eleven.1" c="Eleven.2" />
                    <fx:Object a="12" b="Twelve.1" c="Twelve.2" />
                    <fx:Object a="13" b="Thirteen.1" c="Thirteen.2" />
                </fx:Array>
            </s:source>
        </s:ArrayCollection>
    </fx:Declarations>
    
    <s:Label text="[MyFlexHero.com]:请注意，只有第一列才会出现ToolTip提示！" paddingTop="30"/>
    <mx:DataGrid id="dataGrid" 
                 dataProvider="{MyFlexHero}"
                 rollOverColor="0xE9D2FF"
                 selectionColor="0xC082FF"
                 selectedIndex="3"
                 width="300"
                 rowCount="8">
        <mx:columns>
            <mx:DataGridColumn dataField="a" headerRenderer="mx.controls.Label"
                               headerText="Column 1234567891011121315:" />
            <mx:DataGridColumn dataField="b"  headerRenderer="mx.controls.Label"
                               headerText="Column 123:" />
            <mx:DataGridColumn dataField="c" 
                               headerText="Column 1234567891011121315 这个没有ToolTip:" />
        </mx:columns>
    </mx:DataGrid>

    
</s:Application>