跟我做背景变暗，弹出提示层的功能,而且增加了对Select对象的支持

< html >    
   < head >    
   </ head >    
   < body >    
   < p    align ="center" >    
   < script > ...    
   function    locking() ... {   
  document.all.ly.style.display = " block " ;   
  document.all.ly.style.width = document.body.clientWidth;   
  document.all.ly.style.height = document.body.clientHeight;   
  document.all.Layer2.style.display = ' block ' ;   
  }    
   function    Lock_CheckForm(theForm) ... {   
   if (theForm.P_USERPASS.value == '' ) ... {alert( " 错误：请输入你的用户密码! " );theForm.P_USERPASS.focus(); return     false ;}    
   if (theForm.P_USERPASS.value    != ' 123 ' ) ... {alert( " 错误：密码错误! " );theForm.P_USERPASS.value = '' ;theForm.P_USERPASS.focus(); return     false ;}    
   else ... {document.all.ly.style.display = ' none ' ;document.all.Layer2.style.display = ' none ' ;}    
   return     false ;   
  }    
   </ script >    
   < img    src = >    
    
   </ p >    
   < p    align ="center" >    
    
   < INPUT    TYPE ="button"    value ="系统锁定"    onclick ="locking()" >    
   </ p >    
   < div    id ="ly"    style ="position:absolute;top:0px;FILTER:   alpha(opacity=60);background-color:#777;   z-index:2;   left:   0px;display:none;" >     </ div >    
    
      
               < div    id ="Layer2"    align ="center"    style ="position:absolute;   z-index:3;   width:   540;   height:170px;left:expression((document.body.offsetWidth-540)/2);   top:   expression((document.body.offsetHeight-170)/2);background-color:#fff;display:none;"    valign ="center" >      
   < form    method ="POST"    action =""    onsubmit ="return   Lock_CheckForm(this);" >    
       < TABLE    width =540    height =170    border =0    cellpadding =0    cellspacing =0    style ="border:0   solid   #e7e3e7;border-collapse:   collapse" >    
       < TR >    
       < TD    style ="background-color:#73A2d6;color:#fff;padding-left:4px;padding-top:2px;font-weight:bold;font-size:14px;"    height =27    valign ="center" > [   警   告   ] </ TD >    
       </ TR >    
       < TR >    
       < TD    align ="center"    valign ="center" > 请输入解除锁定密码 < p >< input    type ="text"    name ="P_USERPASS"    size ="20" ></ TD >    
       </ TR >    
       < TR >    
       < TD    height =30    align ="center" >< INPUT    type ="submit"    value ="     确         定     " ></ TD >    
       </ TR >    
       </ TABLE >    
   </ form >    
               </ div >      
      
   </ body >    
   </ html >    
  

  < script    language ="JavaScript" > ...    
      
   </ script >    
   < input    type ="button"    onclick ="showPopup()"    value ="操作有误" >

  < script    language ="JavaScript" > ...    
      
   </ script >    
   < input    type ="button"    onclick ="showPopup()"    value ="操作有误" >