function reservation(sprache,user) {
   if (screen.availHeight > 600) {scrheight = screen.availHeight - 180;} else {scrheight = 460;}
   window.open("http://www.bookingsystem.ch/leoneck/booking.cgi?user="+user+"&lang="+sprache,"booking","menubar=1,location=0,directories=0,toolbar=1,status=1,scrollbars=1,resizable=1,width=680,height="+scrheight);
}