gistfile1.txt

public string GetProductCategory()
        {
            var category = GetFirstCategory(CurrentDocument);
            if (category != null)
            {
                var qsvalue = category.GetValue("CategoryID");

                return "?subject=" + qsvalue;
            }
            else
            {
                return String.Empty;
            }
        }

        public SettingsProvider.BaseInfo GetFirstCategory(TreeNode tn)
        {
            if (tn.Categories != null)
            {
                return tn.Categories.FirstItem;
            }
            else if (!tn.Parent.IsRoot())
            {
                return GetFirstCategory(tn.Parent);
            }
            else
            {
                return null;
            }
        }