div实现可显示隐藏的表情面板的问题

Question

<script>
var flag = true;
function showAndHide(){
document.getElementById('trUserFace').style.display = flag ? "block" : "none";
document.getElementById('divShowAndHide').innerHTML = flag ? "【关闭表情】" : "【使用表情】";
flag = !flag;
}function showimage(index){
document.getElementById("divShowSelectedImg").innerHTML = "<img src=\"" + face_image[parseInt(index) - 1] + "\"/>";
}face_image=new Array(16); 
face_image[0]="http://i3.sinaimg.cn/home/deco/2008/0325/sinahome_Logo.gif"; 
face_image[1]="http://img1.cache.netease.com/cnews/netease/logo.gif"; 
face_image[2]="http://google.cn/intl/zh-CN/images/logo_cn.gif"; 
face_image[3]="http://www.baidu.com/img/baidu_logo.gif";</script><div id="divUserface"> 
<table width="100%" align="center"> 
<tr> 
  <td height="15" colspan="10" align="center" bgcolor="#E7E7E7"> <div id="divShowAndHide" onClick="showAndHide()" style="cursor:hand">【使用表情】</div> </td> 
</tr> 
<tr align="center" valign="middle" id="trUserFace" style="display:none;"> 
<td height="35"> 
<div align="center"> 
<input type="radio" name="userface" value="1" checked onClick="showimage(this.value)"> 
</div>
</td> 
<td  height="35"> 
<div align="center"> <img src="http://i3.sinaimg.cn/home/deco/2008/0325/sinahome_Logo.gif" width="65" height="120"> </div>
</td> 
<td height="35"> 
<div align="center"> 
<input type="radio" name="userface" value="2" onClick="showimage(this.value)"> 
</div>
</td> 
<td  height="35"> 
<div align="center"> <img src="http://img1.cache.netease.com/cnews/netease/logo.gif" width="65" height="120"> </div>
</td> 
<td height="35"> 
<div align="center"> 
<input type="radio" name="userface" value="3" onClick="showimage(this.value)"> 
</div>
</td> 
<td  height="35"> 
<div align="center"> <img src="http://google.cn/intl/zh-CN/images/logo_cn.gif" width="65" height="120"> </div>
</td> 
<td height="35"> 
<div align="center"> 
<input name="userface" type="radio" value="4" width="100%" size="100px" onClick="showimage(this.value)"> 
</div>
</td> 
<td  height="35"> 
<div align="center"> <img src="http://www.baidu.com/img/baidu_logo.gif" width="65" height="120"> </div>
</td> 
</tr> 
</table> 
</div>
<div id="divShowSelectedImg"></div>