var dom = document.getElementById ? true:false;
var nn4 = document.layers ? true:false;
var ie4 = document.all ? true:false;

var numberMenus = 3;
var openMenu = 0;
var closeTimer;

function getLayer(name) {
	var layer;
	if (ie4) layer = document.all[name].style; 
	if (nn4) layer = eval('document.layers["' + name + '"]');
	if (dom) layer = document.getElementById(name).style;
	return layer;
}
	
function hideMenu(menuID) {
	var layer = getLayer("menu_" + menuID);
	layer.visibility = "hidden";
	if (openMenu == menuID) openMenu = 0;
}

function showMenu(menuID) {
	clearTimeout(self.closeTimer);
	if (openMenu > 0) hideMenu(openMenu);
	var layer = getLayer("menu_" + menuID);
	layer.visibility = "visible";
	openMenu = menuID;
}

function stopCloseTimer() {
	clearTimeout(self.closeTimer);
}
	
function startCloseTimer() {
	if (openMenu > 0) self.closeTimer = setTimeout("hideMenu(openMenu);", 100);
}