var w = window;
function openWin(url) {
   if ((w == window) || w.closed) {
      st = "toolbar=0,loation=0,directories=0,status=0,";
      st += "menubar=0,scrollbars=0,resizable=0,top=100,left=100,width=300,height=300";
      w = open(url, "_blank", st);
   } else {
      w.focus();
   }
   return(false);
}