function MM_openBrWindow(theURL,winName,features) { //v2.0
  window.open(theURL,winName,features);
}

function ooFenster(url) {
  MeinFenster = window.open(url, "Zweitfenster", "width=790,height=690,screenx=180,screeny=180,resizeable=no,location=no");
  MeinFenster.focus();
}

newwindow=false;
function fenster(url,breite,hoehe) {
  if(newwindow&&newwindow.closed==false)
    newwindow.close()
    var l = (screen.availWidth - breite) / 2;
    var t = (screen.availHeight - hoehe) / 2;
    newwindow = window.open(url,"newwindow","width=" + breite +
                                            ",height=" + hoehe +
                                            ",left=" + l +
                                            ",top=" + t + ";");
  newwindow.focus();
}