Flex creationPolicy策略

在Flex中，利用state进行状态和页面的迁移与变换，中间的AddChild IOverride有一个creationPolicy，这个属性有三种设置，分别如下：
AUTO：默认设置，只有在状态改变的时候，即时的生成新增组件；
ALL：在Application加载的时候，就加载了新增的组件，在状态改变的时候显示；
NONE：需要手动的调用该addChild Instance createInstance方法生成新增组件，方能显示；
示例代码如下：
<?xml version="1.0"?>
<!-- states\StatesCreationPolicy.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
creationComplete="initButton();">

<mx:Script>
<!--[CDATA[
// Because the cpAll view state creates the Button control
// at application startup, you can access the control to
// set the label before the first switch
// to the cpAll view state.
public function initButton():void {
newButton.label="cpAll Button";
}
]]-->
</mx:Script>
<mx:states>
<!-- Create the Button control at application startup. -->
<mx:State name="cpAll">
<mx:AddChild relativeTo="{myPanel}" creationPolicy="all">
<mx:Button id="newButton"/>
</mx:AddChild>
</mx:State>
<!-- Create the Button control when you want to create it. -->
<mx:State name="cpNone">
<mx:AddChild id="noCP"
relativeTo="{myPanel}" creationPolicy="none">
<mx:Button label="cpNone button"/>
</mx:AddChild>
</mx:State>
</mx:states>

<mx:Panel id="myPanel"
title="Static and dynamic states"
width="300" height="150">

<!-- Change to the cpAll view state. -->
<mx:Button label="Change to cpAll state"
click="currentState