var visibleClass = "main-nav-active";
var invisibleClass = "main-nav-active-hidden";
var currentNavId = null;

// shows an entry in the main nav
function showMainNav(sectionId, navId) {

	if (sectionId == navId) {

		return;
	}

	if (currentNavId != null) {

		hideMainNav(currentNavId);
		currentNavId = null;
	}

	var divId = "nav-" + navId + "-active";
	var div = document.getElementById(divId);
	if (div != null) {

		currentNavId = navId;

		if (document.all) {

			div.setAttribute("className", visibleClass);
		} else {

			div.className = visibleClass;
		}
	}
}

// hides an entry in the main nav
function hideMainNav(navId) {

	var divId = "nav-" + navId + "-active";
	var div = document.getElementById(divId);
	if (div != null) {

		if (document.all) {

			div.setAttribute("className", invisibleClass);
		} else {

			div.className = invisibleClass;
		}
	}
}