function popup(filename, breite, hoehe, titel, windowname, scrolls) {
		oh = hoehe;
		ow = breite;
		
		var ret = screencenter(breite, hoehe, scrolls);
		var breite = ret[0];
		var hoehe = ret[1];
		var l = ret[2];
		var t = ret[3];
		var scrolls = ret[4];
		
		if(filename.indexOf("?") == -1) kupplung = "?";
		else kupplung = "&";
		filename = filename + kupplung + "popuptitle=" + titel + "&w=" + ow + "&h=" + oh;
		newwindow = window.open(filename, windowname,"width="+breite+",height=" +hoehe+",screenX="+l+",screenY="+t+",left=" +l+",top="+t+",location=false,menubar=no,resizable=no,scrollbars="+scrolls+",status=no,toolbar=no");
		newwindow.focus();
		return false;
	}
	
	function screencenter(breite, hoehe, scrolls) {
		if (navigator.userAgent.indexOf("Opera") != -1) 
		{
			var t = (screen.availHeight - hoehe) / 2 - 100;
			var yabstand = 200;
		}
		else {
			var t = (screen.availHeight - hoehe) / 2;
			var yabstand = 50;
		}
		if(breite > screen.availWidth - 50) 
		{
			scrolls = "yes";
			breite = screen.availWidth - 50;
		}
		if(hoehe > screen.availHeight - yabstand) 
		{
			scrolls = "yes";
			hoehe = screen.availHeight - yabstand;
			breite = breite / 1 + 20;
			t = 10;
		}
		var l = (screen.availWidth - breite) / 2;
		
		return new Array(breite, hoehe, l, t, scrolls);
	}