Flex 如何获取Textarea的选择文本

效果：当选择Textarea中的文字时，获取到选择的文字。（有个很大的缺点，选择的时候必须从左往右划词，不能从右往左或者双击划词）

代码如下：

<?xml version="1.0" encoding="utf-8"?>

<!--
* ComingX.com Business License
* 
* Copyright 2012. All rights reserved.
*
* @Author: ShanLanjie
* @Email: shanlanjie#gmail.com
* @Created date: 2012-3-23
-->
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
                       xmlns:s="library://ns.adobe.com/flex/spark"
                       xmlns:mx="library://ns.adobe.com/flex/mx"
                        creationComplete="windowedapplication1_creationCompleteHandler(event)"
                       >
    
        <fx:Script>
        <![CDATA[
            
            import mx.collections.ArrayCollection;
            import mx.events.FlexEvent;
            
            public var mouseDown:Boolean=false;
            public var beginIndex:int;   //记录开始选择的索引
            public var endIndex:int;  //记录选择结束的索引
            public var chooseStr:String;    //记录选择的词语
            public var resultStr:String="";  //记录选择所剩结果
            
            protected function windowedapplication1_creationCompleteHandler(event:FlexEvent):void
            {
                note.addEventListener(MouseEvent.MOUSE_DOWN,onMouseDownHandler);
            }
            
            /* 当鼠标按下时记录第一个字符索引值 */
            public function onMouseDownHandler(evt:MouseEvent):void
            {
                mouseDown=true;
                beginIndex=note.selectionBeginIndex;
                this.note.addEventListener(MouseEvent.MOUSE_MOVE,onMoveHandler);
            }
            
            public function onMoveHandler(evt:MouseEvent):void
            {
                if(mouseDown)
                {
                    this.note.addEventListener(MouseEvent.MOUSE_UP,onMouseUpHandler);
                }    
            }
            
            /* 记录选择完之后的索引值，并处理选择后的逻辑 */
            public function onMouseUpHandler(evt:MouseEvent):void
            {
                endIndex=note.selectionEndIndex;
                chooseStr=note.text.slice( beginIndex,endIndex )  //处理字符串，得到选中的词        
                trace(chooseStr);
            }
            ]]>
    </fx:Script>
    
    <mx:TextArea width="800" height="50" id="note"  fontSize="14" fontWeight="bold" editable="false" selectable="false" text="注意：选择词语的时候必须从左到右选择，不能双击选择或者从右往左选择"/>
    </s:WindowedApplication>