var last_menu = null;
function slide_menu(elem) {
	node = elem.parentNode;
	if (node.className.search('closed') != -1) {
		node.className = 'side_menu';

		if (last_menu == null)
			last_menu = document.getElementById('side_menu_opened');

		if (last_menu != null)
			last_menu.className = 'side_menu closed';

		last_menu = node;
	} else
		node.className = 'side_menu closed';
}