CH03_08.mxml 两个文本框绑定赋值为一个文本框

<?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">
  <s:Group>
    <s:layout>
      <s:HorizontalLayout/>
    </s:layout>
    <s:TextInput id="myTextInput1"/>
    <s:TextInput id="myTextInput2"/>    
    <s:TextInput id="myTextInput3" text="{myTextInput1.text + myTextInput2.text}"/>
  </s:Group>
</s:Application>