function popup_window(fileName,wname,w,h) 
{
   var winl = (screen.width - w) / 2;
   var wint = (screen.height - h) / 2;
   var winprops = 'height='+h+',width='+w+',resizable=no,location=no,menubar=no,status=no,menubar=no,toolbar=no';
   winopen = window.open(fileName,'',winprops);
}