var w = null;

function b(n) {
   if (w && w.open && !w.closed) w.close();
   w = window.open(n+".htm", "w","toolbar=yes,directories=no,status=no,menubar=yes,scrollbars=yes,resizable=yes,width=670,height=350");
}

function closew() {
  if (w && w.open && !w.closed) w.close();
}