密码框选中后无法取消

用document.selection.empty()<html> 
<head> 
<title> test </title> 
<script language='javascript'> 
function onfocusevent() { 
    var   e=event.srcElement 
    e.focus(); 
    e.select(); 
} 
</script> 
<body> 
<input   type="text"   ID="name"   onfocus="onfocusevent()" onblur="document.selection.empty()" value="testname"   /> 
<input   type="password"   ID="pwd"     onfocus="onfocusevent()" onblur="document.selection.empty()" value="54545"   /> 
<input   type="radio"   id="rao"   value="radiobutton"   /> 
<input   type="submit"   name="Submit"   value="提交"   /> 
</body> 
</html>