function popup(datei, b, h) {
	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=no, resizable=no");
	fenster.focus();
}