* @param T Type of the widget (e.g. wxSpinCtrl)
* @param U Data type of state as used by the model.
* @param V Data type of state as used by the view.
*/
template <class S, class T, typename U, typename V>
* @param T Type of the widget (e.g. wxSpinCtrl)
* @param U Data type of state as used by the model.
* @param V Data type of state as used by the view.
*/
template <class S, class T, typename U, typename V>