// JavaScript Document
function popup(datei) {
  var b = 500;
  var h = 500;
  var x = screen.width/2 - b/2;
  var y = screen.height/2 - h/2;
  fenster = window.open(datei, "_blank", "width="+b+", height="+h+", left="+x+", top="+y+", scrollbars=yes, resizable=no");
}