function openWindow(url,windowName,width,height,scrollbars) { 
  var left=(screen.width)?(screen.width-width)/2:100;
  var top=(screen.height)?(screen.height-height)/2:100;
  settings='width='+width+',height='+height+',top='+top+',left='+left+',scrollbars='+scrollbars+',location=no,directories=no,status=0,menubar=no,toolbar=no,resizable=no';
  window.open(url,windowName,settings);
}