var timeout	= 500;
var timer = 0;
var dropMenu = 0;

// open menu
function openMenu(id)
{	
	// cancel close timer
	cancelTimer();

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

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

}

// close menu
function menuClose()
{
	if(dropMenu) dropMenu.style.visibility = 'hidden';
}

// start timer
function startTimer()
{
	timer = window.setTimeout(menuClose, timeout);
}

// cancel timer
function cancelTimer()
{
	if(timer)
	{
		window.clearTimeout(timer);
		timer = null;
	}
}

// close layer when click-out
document.onclick = menuClose();