function FensterOeffnen (Adresse) {
  MeinFenster = window.open(Adresse, "Zweitfenster", "width=800,height=585,left=100,top=100");
  MeinFenster.focus();
}
links = (screen.Width-860)/2;
oben = (screen.Height-540)/2;
function aktuelles (Adresse1) {
  Fenster = window.open(Adresse1, "Drittfenster", "width=400,height=580,left="+links+",top="+oben+"");
  Fenster.focus();
}