function openWindow(url, width, height, resizable, targetName) {
  wleft = (screen.width - width - 16) / 2;
  wtop  = (screen.height - height - 30) / 2;
  window.open(url, targetName, 'toolbar=no,location=no,directories=no,scrollbars=yes,status=no,menubar=no,resizable='+resizable+',width='+width+',height='+height+',left='+wleft+',top='+wtop);
}