function fenster(url, name, breite, hoehe, parameter) {
    	var screenbreite;
    	var screenhoehe;
    	var linkerRand;
    	var obererRand;
    	screenbreite = screen.width;
    	screenhoehe = screen.height;
    	if (screenbreite > 1600) {
       	 linkerRand = Math.round(((screenbreite / 2) - breite) / 2);
    	}else{
        	linkerRand = Math.round((screenbreite - breite) / 2);
    	}
    	obererRand = Math.round((screenhoehe - hoehe) / 100 * 35);
        parameter = 'width=' + breite + ', height=' + hoehe + ',left=' + linkerRand + ',top=' + obererRand + ', ' + parameter; popup = window.open(url, name, parameter); popup.focus();
	}