// vars
	var menuId = "menu";
	
	// comportamento do menu
	menuBehavior = function()
	{		
		
		// recolher submenus
		var menu = document.getElementById(menuId);
					var submenus = menu.getElementsByTagName("ul");
					for (var i=0; i < submenus.length; i++){
					submenus[i].style.display = "none";}
					
		// adicionar comportamento aos itens do menu
			 		var itens = menu.getElementsByTagName("a");
					for (var i=0; i < itens.length; i++){
					addEvent(itens[i], "click", itenBehavior);}
		
	}
	// comportamento dos itens do menu
	itenBehavior = function(e)
	{
									
				// ver quem disparou o evento
			 		e = (typeof(e) == "undefined") ? window.e : e;					
					var quemDisparou = !e.target ? e.srcElement : e.target;
					if (quemDisparou.nodeType == 3)
					quemDisparou = quemDisparou.parentNode;					
					
			  // expandir ou recolher sub-menu
					 var parent = quemDisparou.parentNode;
					 var submenu = parent.getElementsByTagName("ul")
					 
					 if(submenu.length > 0)
					 submenu[0].style.display = (submenu[0].style.display  == "none") ? "block":"none";
	
	}
		
	// iniciando comportamentos  
	initBehaviors = function()
	{
		menuBehavior();
	}
	
	addEvent = function(obj, evType, fn)
	{
		var w3DOM = obj.addEventListener;
		var ieDOM = obj.attachEvent;
		if (w3DOM)  obj.addEventListener(evType, fn, true);
		if (ieDOM)  obj.attachEvent("on"+evType, fn);
	}
	
	addEvent(window, "load", initBehaviors);