function winOpen (url, breite, hoehe) {
      // Errechnet Koordinaten, um das Popup zentriert zu platzieren
      links = (screen.width/2)-(breite/2);
      oben = (screen.height/2)-(hoehe/2);
      window.open(url,'popup','height='+hoehe+',width='+breite+',status = no,toolbar = no,menubar = no,location = no,resizable = no,titlebar = no,scrollbars = no,fullscreen = no,top ='+oben+',left ='+links);
   }