框架问题

//用IFrame的<html>
<head><title>FrameDemo</title>
<script language="Javascript" >
function changeLeftWidth(obj)
{
if(obj.innerText=="<")
{
theLeftTd.width=1;
obj.innerText=">"
}
else
{
theLeftTd.width=170;
obj.innerText="<"
}
}
</script>
</head>
<body scroll="no" leftMargin="0" rightMargin="0" topMargin="0" bottomMargin="0" >
<table border="0" cellPadding=0 cellSpacing=0 bgcolor="#FFFFFF" width="100%" height=100% valign="top"  
leftMargin="0" rightMargin="0" topMargin="0" bottomMargin="0" >
<tr><td height="75" colspan=3>
<iframe src="about:blank" align="top" scrolling="no" height="75" width="100%" frameborder="0" name="menuframe"></iframe>
</td></tr>
<tr>
<td width=170 id=theLeftTd>
<iframe src="about:blank" width="100%" height="100%" scrolling="no" frameborder="0" name="folderframe"></iframe>
</td>
<td bgcolor=cccccc width="1" onclick=changeLeftWidth(this)><</td>
<td>
<iframe src="about:blank" width="100%" height="100%" scrolling="auto" frameborder="0" name="clientframe"></iframe>
</td>
</tr>
</table>
</body>
</html>