function getByID(id) {
	return document.getElementById(id);
}
function openMenu(id) {
	var div,link;
	if (div = getByID('DIV_' + id)) div.style.display = 'block';
	if (link = getByID('ID_' + id)) replaceClass(link, 'submenu', 'submenu_open');
}
function closeMenu(id) {
	var div,link;
	if (div = getByID('DIV_' + id)) div.style.display = 'none';
	if (link = getByID('ID_' + id)) replaceClass(link, 'submenu_open', 'submenu');
}
function toggleMenu(id) {
	var link;
	if (link = getByID('ID_' + id)) {
		if (hasClass(link, 'submenu_open')) closeMenu(id); else openMenu(id);
	}
}