public List<T> GetChildObjects<T>(DependencyObject obj, Type typename) where T : FrameworkElement

        {

            DependencyObject child = null;

            List<T> childList = new List<T>();

            for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(obj) - 1; i++)

            {

                child = VisualTreeHelper.GetChild(obj, i);

                if (child is T && (((T)child).GetType() == typename))

                {

                    childList.Add((T)child);

                }

                childList.AddRange(GetChildObjects<T>(child, typename));

            }

            return childList;

        }

 List<TextBlock> listTextBlock = GetChildObjects<TextBlock>(dgSimple, typeof(TextBlock));