Flex4 布局 元素index

<?xml version="1.0" encoding="utf-8"?>
<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"
height="730">
<s:layout>
<s:BasicLayout/>
</s:layout>

<fx:Script>
<![CDATA[
protected function btn001_clickHandler(event:MouseEvent):void{
trace(win001.getElementIndex(btn001));
win001.setElementIndex(btn001,0);
}
protected function btn002_clickHandler(event:MouseEvent):void{
var lbl:Label = new Label();
lbl.text = 'created label';
win001.addElement(lbl);
}

protected function btn003_clickHandler(event:MouseEvent):void{
win001.removeElement(btn002);
var getChildAt2:DisplayObject = win001.getChildAt(0);
trace(getChildAt2);
}

protected function btn004_clickHandler(event:MouseEvent):void{
win001.swapElements(lbl002,lbl003);
}

protected function btn005_clickHandler(event:MouseEvent):void{
var lbl002Index:int = win001.getElementIndex(lbl002);
var lbl003Index:int = win001.getElementIndex(lbl003);
trace(lbl002Index);
trace(lbl003Index);
win001.swapElementsAt(lbl002Index,lbl003Index);
}

]]>
</fx:Script>

<fx:Declarations>
<s:RadioButtonGroup id="radiogroup1"/>
<!-- 将非可视元素（例如服务、值对象）放在此处 -->
<!-- 选中text之后，再点击别的地方，才会出现提示，仅有空格都不行，会有默认消息 -->
<mx:StringValidator source="{txt001}" id="vld001" property="text" requiredFieldError="ABC...">
</mx:StringValidator>
<!-- 不输入不会出提示，输入一个会有提示，两个空格就可以 -->
<mx:StringValidator source="{txt002}" id="vld002" property="text" required="false" minLength="2" tooShortError="DEF..." >
</mx:StringValidator>
</fx:Declarations>
<s:Form x="316" y="21" width="240" height="187">
<s:FormHeading label="In a Form"/>
<s:FormItem label="标签" required="true">
<s:TextInput id="txt001"/>
</s:FormItem>
<s:RadioButton label="按钮 1" groupName="radiogroup1"/>
<s:RadioButton label="按钮 2" groupName="radiogroup1"/>
<s:FormItem label="标签">
<s:TextInput id="txt002"/>
</s:FormItem>
</s:Form>
<s:Panel x="27" y="21" width="250" height="158" title="This is panel">
<s:TileGroup x="10" y="10" width="228" height="105">
<s:Label text="In a TileGroup"/>
<s:Button label="按钮"/>
<s:CheckBox label="复选框"/>
<mx:ColorPicker/>
<mx:DateField formatString="YYYY-MM-DD" yearNavigationEnabled="true"/>
</s:TileGroup>
</s:Panel>
<s:TitleWindow id="win001" x="27" y="216" width="250" height="200" title="This is TitleWindow">
<s:Label id="lbl001" x="23" y="20" backgroundColor="#EE1717" text="in the titleWindow"/>
<s:Button id="btn001" x="96" y="12" label="get/setElementIndex" click="btn001_clickHandler(event)"/>
<s:Label id="lbl002" x="23" y="40" backgroundColor="#16FE04" text="this is green"/>
<s:Label id="lbl003" x="66" y="40" backgroundColor="#FFFF00" text="this is yellow"/>
<s:Button id="btn002" x="19" y="60" label="addElement" click="btn002_clickHandler(event)"/>
<s:Button id="btn003" x="114" y="60" label="removeElement" click="btn003_clickHandler(event)"/>
<s:Button id="btn004" x="20" y="89" label="swapElements" click="btn004_clickHandler(event)"/>
<s:Button id="btn005" x="20" y="118" label="swapElementsAt" click="btn005_clickHandler(event)"/>
<s:Spacer x="161" y="42" width="43" height="10"/>
</s:TitleWindow>
<s:TileGroup x="316" y="216" width="240" height="200" paddingTop="5">
<s:Label text="In a TileGroup"/>
<s:Spacer width="10" height="10"/>
</s:TileGroup>
<s:SkinnableContainer x="578" y="21" width="152" height="158">
<s:Label x="10" y="27" text="In a SkinnableContainer"/>
<s:Line x="11" y="48" width="116" height="71" xTo="40">
<s:stroke>
<s:SolidColorStroke color="black" weight="2">

</s:SolidColorStroke>
</s:stroke>
</s:Line>
</s:SkinnableContainer>
<s:HGroup x="578" y="216" width="152" height="78" paddingTop="5">
<s:Label text="inHGroup"/>
<s:Button label="按钮"/>
<s:Button label="按钮"/>
</s:HGroup>
<s:VGroup x="578" y="329" width="152" height="87" horizontalAlign="contentJustify" paddingLeft="5" paddingTop="5" verticalAlign="top">
<s:Label text="inVGroup"/>
<s:Button label="按钮"/>
<s:Button label="按钮"/>
</s:VGroup>
<s:Panel x="23" y="438" width="250" height="200" title="mx:HDividedBox和mx:VDividedBox">
<s:layout>
<s:HorizontalLayout/>
</s:layout>
<mx:HDividedBox width="100%" height="100%">
<s:BorderContainer height="100%" width="25%">
</s:BorderContainer>
<s:BorderContainer height="100%" width="75%">
<mx:VDividedBox width="100%" height="100%">
<s:BorderContainer height="100%" width="100%">
</s:BorderContainer>
<s:BorderContainer height="100%" width="100%">
</s:BorderContainer>
<s:BorderContainer height="100%" width="100%">
</s:BorderContainer>
</mx:VDividedBox>
</s:BorderContainer>
</mx:HDividedBox>
</s:Panel>
<s:Panel right="193" bottom="92" width="250" height="200" title="基于约束的布局">
<s:Button left="20" right="158" top="21" bottom="125" label="按钮"  horizontalCenter="-69" verticalCenter="-52"/>
</s:Panel>
</s:Application>