<BR><BR><center>
将鼠标移过来看效果！
<BR><BR>
<input type="text" name="LoginName" size="20" value="用户名" onMouseOver="this.focus()" onMouseOut="if(this.value=='')this.value='用户名';" onFocus="this.select()" onClick="if(this.value=='用户名')this.value=''">