递归查找指定节点

 private ItemTreeModel GetModel(List<ItemTreeModel> list, string Header)
        {
            foreach (var item in list)
            {
                if (item == null)
                    continue;
                else if (item.ItemHeader == Header)
                    return item;
                else if (item.ItemParent.Count > 0)
                {
                    ItemTreeModel model = GetModel(item.ItemParent, Header);
                    if (model.Header != null)
                        return model;
                }
            }
            return null;
        }