// JavaScript Document
function fenster(url,breite,hoehe,extoptions) {
  var url;
  var width=breite;
  var height=hoehe;
  var l = (screen.availWidth - width) / 2;
  var t = (screen.availHeight - height) / 2;
  newwindow = window.open(url,"newwindow","width="+breite+",height=" +hoehe+",screenX="+l+",screenY="+t+",left=" +l+",top="+t+","+extoptions);
  newwindow.focus();
}