function getVisibleLayers() {
	var visibleLayers = new Array;
	for (i in menu) {
                var layeridtmt = document.getElementById('layer_' + menu[i]);
		if (layeridtmt.style.visibility != 'hidden') {
			visibleLayers.push(menu[i]);
		};
	};
	visibleLayers.shift();
	visibleLayers.shift();
	return visibleLayers;
};