var submenu_timeout = null;

function showSubmenu() {
	if (submenu_timeout) {
		clearTimeout(submenu_timeout);	
	}
	var submenu = document.getElementById('submenu');
	submenu.style.visibility = 'visible';
}

function hideSubmenu(enable) {
	var submenu = document.getElementById('submenu');
	if (enable) {
		submenu_timeout = setTimeout("hideSubmenu(false);", 300);
	} else {
		submenu.style.visibility = 'hidden';
	}
}