var image_root = "../../img/";

//argument topic musi byt string
function menu_on(topic) {
	image = image_root + "vlak/" + topic + "_r.gif";
	document[topic].src = image;
	document['masina'].src = image_root + "vlak/masina_r.gif";
};

//argument topic musi byt string
function menu_off(topic) {
	image = image_root + "vlak/" + topic + ".gif";
	document[topic].src = image;
		document['masina'].src = image_root + "vlak/masina.gif";
};