GetControls & GetControlsRecursive

public static class ControlExtender
    {
        /// <summary>
        /// Recursively finds controls of Type T, started from the root.
        /// </summary>
        /// <typeparam name="T">Type of the returned controls</typeparam>
        /// <param name="root">Root control to starts from</param>
        public static IEnumerable<T> GetControlsRecursive<T>(this Control root) where T : Control
        {
            foreach (T control in root.Controls.OfType<T>())
            {
                yield return (T)control;

                if (control.HasControls())
                {
                    foreach (T childControl in GetControls<T>(control))
                    {
                        yield return childControl;
                    }
                }
            }
        }

        /// <summary>
        /// Finds controls of Type T.
        /// </summary>
        /// <typeparam name="T">Type of the returned controls</typeparam>
        /// <param name="controlToSearch">Control to search</param>
        public static IEnumerable<T> GetControls<T>(this Control controlToSearch) where T : Control
        {
            foreach (T child in controlToSearch.Controls.OfType<T>())
            {
                yield return (T)child;
            }
        }
    }