使用window对象实现弹出窗口

DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
< HTML >
  < HEAD >
   < TITLE >  New Document  TITLE >
   < META  NAME ="Generator"  CONTENT ="EditPlus" >
   < META  NAME ="Author"  CONTENT ="" >
   < META  NAME ="Keywords"  CONTENT ="" >
   < META  NAME ="Description"  CONTENT ="" >
   < script > ...
    function aa()...{
      var a=window.createPopup();
          var p=a.document.body;
          p.style.backgroundColor="#ffff99";
          p.style.border="solid black 1px"
          p.innerHTML="123";
      a.show(50,50,50,50,document.body);
    }
   script >
  HEAD >

  < BODY >
   < input  type ="button"  value ="11"  onclick ="aa();" />
  BODY >
HTML >