			findSibling = function(subtree, dir) {
				var node = subtree.children(':first'),
					info, compare;

				compare = fm.naturalCompare;
				while (node.length) {
					info = fm.file(fm.navId2Hash(node.children('[id]').attr('id')));
					
					if ((info = fm.file(fm.navId2Hash(node.children('[id]').attr('id')))) 
					&& compare(dir.name, info.name) < 0) {
						return node;
					}
					node = node.next();
				}
				return $('');
			},