Flex TextArea Unicode chracters with control key

I am developing a Flex based window application. In that I have used a textArea, Now when I type some characters like ctrl+b, ctrl+e or ctrl+q, it shows some square characters in text area, I think these are some unicode characters but why these are being entered.

Unlike in simple textArea control on adobe example when I presses these key combination, there is nothing being entered, so why this only with me.

This is my window setup code

<?xml version="1.0" encoding="utf-8"?>
    <mx:WindowedA开发者_运维技巧pplication xmlns:mx="http://www.adobe.com/2006/mxml" 
        layout="absolute" 
        showFlexChrome="false"
        creationComplete="initApplication(); "
        applicationComplete="txtArea.setFocus();"
        width="310" alwaysInFront="true"    
        showTitleBar="false" showStatusBar="false"
        height="350" resizing="true" frameRate="7" >

and this is my textArea control

<mx:TextArea tabIndex="1" id="message" height="159" width="266" 
    focusEnabled="true" focusThickness="0" scroll="1" backgroundAlpha="0.4" 
    backgroundColor="{panel.getStyle('backgroundColor')}" borderColor="#CCCCCC" 
    styleName="textarea" borderThickness="1" change="whileType()" 
    maxChars="5120" verticalScrollBarStyleName="scrollbar" cornerRadius="4" >
</mx:TextArea> 

Please help me to solve this?

Thanks, Jaswant

consider adding the following property to your TextArea:

        restrict="A-Z a-z 0-9 !@#$%^*-+[]{}()"

helped in my case, as for exam it fixed an extra char showing after Ctrl+Backspace