public override void BuildChildNodes(ITreeBuilder builder, object dataObject)
        {
            ValaProject p = dataObject as ValaProject;

            if (p == null)
            {
                return;
            }

            // bool nestedNamespaces = builder.Options["NestedNamespaces"];

            ProjectInformation info = ProjectInformationManager.Instance.Get(p);

            // Namespaces
            foreach (ProjectFile file in p.Files)
            {
                foreach (Symbol child in info.GetNamespacesForFile(file.FilePath.FullPath))
                {
                    builder.AddChild(child);
                }
            }
        }