public DiagnosticMenuTag(IDiagnosticContext context, ICurrentHttpRequest currentHttpRequest, IUrlRegistry urls) : base("ul")
        {
            AddClass("nav");

            var group = context.CurrentGroup();

            var index = group.Index();
            if (index != null)
            {
                addLink(index, context, currentHttpRequest);
            }
            else
            {
                var url = urls.UrlFor(new GroupRequest {Name = group.Name});
                var li = Add("li");
                li.Add("a").Attr("href", url).Text(group.Name).Attr("title", group.Description);

                if (context.CurrentChain() == null)
                {
                    li.AddClass("active");
                }
            }

            group.Links().Each(x => addLink(x, context, currentHttpRequest));
        }