function fenster_oeffnen() {
  if (fenster_oeffnen.arguments.length == 3)
    var w = window.open(fenster_oeffnen.arguments[0],
                        fenster_oeffnen.arguments[1],
                        fenster_oeffnen.arguments[2]);
  else if (fenster_oeffnen.arguments.length == 2)
    var w = window.open(fenster_oeffnen.arguments[0],
                        fenster_oeffnen.arguments[1]);
  else if (fenster_oeffnen.arguments.length == 1)
    var w = window.open(fenster_oeffnen.arguments[0]);
  else if (fenster_oeffnen.arguments.length == 0)
    var w = window.open();

  if (w)
    if (!w.opener)
      w.opener = self;

  return w;
}