function submenu_show(submenu)
{
	if(document.prev_menu)
	{
		document.getElementById(document.prev_menu).style.visibility = 'hidden';
	}
	if(document.active_menu)
	{
		document.getElementById(document.active_menu).style.visibility = 'hidden';
	}
	document.prev_menu = submenu;
	document.getElementById(submenu).style.visibility = 'visible';
}

function submenu_hide()
{
	if(document.prev_menu)
	{
		document.getElementById(document.prev_menu).style.visibility = 'hidden';
	}
	if(document.active_menu)
	{
		document.getElementById(document.active_menu).style.visibility = 'visible';
	}
}