function popUp(url,pageName,w,h) {
  leftPos=(screen.width)?(screen.width-w)/2:100;
  topPos =(screen.height)?(screen.height-h)/2:100;
  settings='width='+w+',height='+h+',top='+topPos+',left='+leftPos+',scrollbars=no,location=no,directories=no,status=no,menubar=no,toolbar=no,resizable=yes';
  window.open(url,pageName,settings);
  return false;
}