function treeExpand(id) {
	var obj = $('exdiv/' + id.split('/').slice(3).join('/'));
	if (obj) {
		if (Element.hasClassName(id, 'tree-minus')) {
			Element.removeClassName(id, 'tree-minus');
			Element.addClassName(id, 'tree-plus');
		}
		else {
			Element.removeClassName(id, 'tree-plus');
			Element.addClassName(id, 'tree-minus');
		}
		Element.toggle(obj);
		return;
	}
	var req = new Ajax.Request(AppAjaxPath + id, {
		method: 'post',
		onComplete: treeUpdate
	});
}

function treeUpdate(req) {
	var ret = parseJson(req.responseText);
	if (typeof ret['status'] == 'undefined' || ret['status'] == 0) {
		alert('Error!\n' + ret['data']);
		return;
	}
	new Insertion.Bottom('collapse/' + ret['id'].split('/').slice(3).join('/'), ret['data']);
	Element.removeClassName(ret['id'], 'tree-plus');
	Element.addClassName(ret['id'], 'tree-minus');
	_formCenter();
}