// these are placeholders not parmater, they are overitten.
var navmenutimer = 0;
var navmenuitem0 = 0;
// open hidden layer
function navopen(id0)
{	
	// cancel close timer
	undonavclosetime();
	// close old layer
	if(navmenuitem0) navmenuitem0.style.visibility = 'hidden';
	// get new layer and show it
	navmenuitem0 = document.getElementById(id0);
	navmenuitem0.style.visibility = 'visible';
}
// close showed layer
function navclose()
{
	if(navmenuitem0) navmenuitem0.style.visibility = 'hidden';
}
// go close timer
function navclosetime()
{
	navmenutimer = window.setTimeout(navclose, 100);
}
// cancel close timer
function undonavclosetime()
{
	if(navmenutimer)
	{
		window.clearTimeout(navmenutimer);
		navmenutimer = null;
	}
}
// close layer when click-out
document.onclick = navclose;