function winOpen(url, breite, hoehe) {
  links = (screen.width/2)-(breite/2);
  oben = (screen.height/2)-(hoehe/2);
  window.open(url,"pop_up","height="+hoehe+",width="+breite+",status = no,toolbar = no,menubar = no,location = yes,resizable = yes,titlebar = yes,scrollbars = yes,fullscreen = no,top ="+oben+",left ="+links);
}