var old_menu_know = new Array('','');

function know_menuclick(num, menu_depth) {
	var submenu = document.getElementById(num);

	if(old_menu_know[menu_depth] != submenu) {
		if(old_menu_know[menu_depth] != '') old_menu_know[menu_depth].style.display = 'none';
		submenu.style.display = 'block';
		old_menu_know[menu_depth] = submenu;
	} else {
		submenu.style.display = 'none';
		old_menu_know[menu_depth] = '';
	}
}