function NewWindow(mypage, myname, w, h) 
{
  var winl = (screen.width - w) / 2;
  var wint = (screen.height - h) / 2;
  winprops = 'height='+h+', width='+w+', top='+wint+', left='+winl;
  win = window.open(mypage, myname, winprops);
}