var gOpenMenuId = null;

function showMenu(id) {
	if (gOpenMenuId != null)
		hideMenu(gOpenMenuId);

	var menu  = document.getElementById(id);
	menu.style["display"] = "block";
	gOpenMenuId = id;
}

function hideMenu(id) {
	document.getElementById(id).style["display"] = "none";
	gOpenMenuId = null;
}