var timeout	= 500;
var close	= 0;
var sub_menu	= 0;

// open hidden layer
function sub_over(id)
{	
	// cancel close timer
	timer_close();

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

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

}
// close showed layer
function click_out()
{
	if(sub_menu) sub_menu.style.visibility = 'hidden';
}

// go close timer
function sub_out()
{
	close = window.setTimeout(click_out, timeout);
}

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

// close layer when click-out
document.onclick = click_out;