function popup (datei) {
		var b = 900;
		var h = 350;
		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");
}