var newWindow = null;
var windowClosed = true;

function popupOpen(url,w,h)
{
  if (newWindow != null || !windowClosed) {
    newWindow.close();
  }
  else {
    windowClosed = true;
  }

  newWindow=window.open(url, '','left=10,top=30,width=' + w + ',height=' + h + ',toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=no,copyhistory=no');
  windowClosed = false;
  newWindow.focus();
}