var nav_menu = null;
var nav_submenu = null;

function show(id)
{
    if (!isDOMcompliant()) { return; }
    var menu = document.getElementById("Menu" + id);
    var menus = document.getElementById("NavMenuList");
    var submenu = menus.getElementsByTagName("ul").item(id);
    
    if (nav_submenu == null) {
        submenu.style.visibility = "visible";
        highlightFirstItem(id); 
    } else {
        nav_submenu.style.visibility = "hidden";
        submenu.style.visibility = "visible";
	highlightFirstItem(id);    
    }
    
    if (nav_menu == null) {
        menu.style.backgroundColor = "#FFF";
        menu.style.color = "#000";
    } else {
        nav_menu.style.backgroundColor = "#69C";
        nav_menu.style.color = "#FFF";
        menu.style.backgroundColor = "#FFF";
        menu.style.color = "#000";
    }
    nav_menu = menu;
    nav_submenu = submenu;
}

function isDOMcompliant()
{
    return document.getElementById && document.getElementsByTagName;
}

function highlightFirstItem(id){
    if (!isDOMcompliant()) { return; }
    var menu = document.getElementById("Menu" + id);
    var menus = document.getElementById("NavMenuList");
    var submenu = menus.getElementsByTagName("ul").item(id);
    var submenuItems = submenu.getElementsByTagName("li");
    var firstSubmenuItem = null;
    if( submenuItems != null ){
    	firstSubmenuItem = submenuItems.item(0);
    }
    if(firstSubmenuItem != null){
	ahrefs = firstSubmenuItem.getElementsByTagName("a");
	if(ahrefs.item(0) != null){
		ahrefs.item(0).style.background="#CCC";	
	}
    }
}

function unhighlightFirstItem(id){
    if (!isDOMcompliant()) { return; }
    var menu = document.getElementById("Menu" + id);
    var menus = document.getElementById("NavMenuList");
    var submenu = menus.getElementsByTagName("ul").item(id);
        var submenuItems = submenu.getElementsByTagName("li");
        var firstSubmenuItem = null;
        if( submenuItems != null ){
        	firstSubmenuItem = submenuItems.item(0);
        }
        if(firstSubmenuItem != null){
    		ahrefs = firstSubmenuItem.getElementsByTagName("a");
    		if(ahrefs.item(0) != null){
    			ahrefs.item(0).style.background="#FFF";		
    		}
        }

}