// Modifizierte Version des Popup-Scripts von
// http://1ngo.de/web/popup.html
function popup(w, h, target, title) {
  h -= 20;

  var x = 0, y = 0, parameters = "";

  if (w < screen.availWidth || h < screen.availHeight) {
    x = (screen.availWidth - w - 12) / 2;
    y = (screen.availHeight - h - 104) / 2;

    if (window.opera)
      y = 0; // Opera positioniert unter den Symbolleisten

    if (x < 0 || y < 0) {
      x = 0;
      y = 0;
    }
    else {
      parameters = "width=" + w + ",height=" + h + ",";
    }
  }

  parameters += "left=" + x + ",top=" + y +
                ",menubar=yes,location=yes,toolbar=no,status=no" +
                ",resizable=yes,scrollbars=yes";

  var wnd = window.open(target, title, parameters);

  if (wnd)
    wnd.focus();

  return !wnd;
}