// class manipulation

function setClassname(id, classname){ document.getElementById(id).className = classname; }
function getClassname(id){ return document.getElementById(id).className; }
function replaceClassname(id, find, replace){ setClassname(id, getClassname(id).replace(new RegExp(find), replace)); }

/* show hide drop down menus */

var old_menu = null, hide = null;
function hide_menu(id){
	if(id == null) return;
	obj = document.getElementById('dropnav-' + id);
	navobj = 'nav-' + id;
	if(obj) obj.style.visibility = 'hidden';
    if(navobj) replaceClassname(navobj, 'nav_mouseon', 'nav_mouseoff');
	clear_timeout();
}

function show_menu(id){
	if(old_menu) hide_menu(old_menu);
	obj = document.getElementById('dropnav-' + id);
	navobj = 'nav-' + id;
	if(obj){
		obj.style.visibility = 'visible';
	    obj.className = 'menu_navigation';
	}
	if(navobj){
	    replaceClassname(navobj, 'nav_mouseoff', 'nav_mouseon');
	}
	old_menu = id;
	clear_timeout();
}

function set_timeout(){
	hide = setTimeout("hide_menu('" + old_menu + "')",700);
}

function clear_timeout(){
	clearTimeout(hide);
}