function sub_window() {
          w=window.open("","sub_window","toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,dependent=no,width=400,height=300,screenX=0,screenY=0,left=0,top=0");
          if (navigator.appVersion.charAt(0) >= 3) {
            w.focus();
          }
        }