protected virtual void OnViewMonthChanged(DateChangedEventArgs e)
        {
            if (ViewMonthChanged != null)
            {
                ViewMonthChanged(this, e);
            }

            ViewMonth = DefaultCalendar.GetMonth(e.NewValue.Value);
        }
        protected virtual void OnSelectedMonthChanged(DateChangedEventArgs e)
        {
            if (SelectedMonthChanged != null)
            {
                SelectedMonthChanged(this, e);
            }

            SelectedMonth = e.NewValue.HasValue ? DefaultCalendar.GetMonth(e.NewValue.Value) : -1;
        }