var timeout	= 100;
var closetimer	= 0;
var nav_menu_item	= 0;

function nav_menu_open(id)
{	
	nav_menu_cancel();

	if(nav_menu_item) nav_menu_item.style.visibility = 'hidden';

	nav_menu_item = document.getElementById(id);
	nav_menu_item.style.visibility = 'visible';	
}

function nav_menu_close()
{
	if(nav_menu_item) nav_menu_item.style.visibility = 'hidden';
}

function nav_menu_close_time()
{
	closetimer = window.setTimeout(nav_menu_close, timeout);
}

function nav_menu_cancel()
{
	if(closetimer)
	{
		window.clearTimeout(closetimer);
		closetimer = null;
	}
}

document.onclick = nav_menu_close;