var nav_timeout	= 500;
var nav_closetimer	= 0;
var nav_menuitem	= 0;

function nav_display(id) {
	nav_cancelclose();
	if(nav_menuitem){
		nav_menuitem.style.visibility = 'hidden';
	}
	nav_menuitem=document.getElementById(id);
	nav_menuitem.style.visibility = 'visible';
}

function nav_closedropdown() {
	if(nav_menuitem){
		nav_menuitem.style.visibility = 'hidden';
	}
}

function nav_closedelay() {
	nav_closetimer = window.setTimeout(nav_closedropdown, nav_timeout);
}

function nav_cancelclose() {
	if(nav_closetimer)
	{
		window.clearTimeout(nav_closetimer);
		nav_closetimer=null;
	}
}
document.onclick = nav_closedropdown;