var timeout = 500;
var closetimer = 0;
var ddmenuitem = 0;

function showMenu(id) {
    // Stop the timer
    menuCancelClose();

	// close old layer
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';

	// get new layer and show it
	ddmenuitem = document.getElementById(id);
	ddmenuitem.style.visibility = 'visible';
}

function closeMenu() {
    if(ddmenuitem) ddmenuitem.style.visibility = "hidden";
}

function menuCloseTimer() {
    closetimer = window.setTimeout(closeMenu, timeout);
}

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

document.onClick = closeMenu;