private static void OnTextPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            //To be called whenever the DP is changed.
            TwoIntegerNumericUpDown tinup = sender as TwoIntegerNumericUpDown;

            if (tinup != null && e.NewValue != null)
            {
                tinup.textBoxValue.Text = e.NewValue.ToString();
            }
        }
        private static void OnButtonsIntervalPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            //To be called whenever the DP is changed.
            TwoIntegerNumericUpDown tinup = sender as TwoIntegerNumericUpDown;

            if (tinup != null)
            {
                tinup.upButton.Interval   = (int)e.NewValue;
                tinup.DownButton.Interval = (int)e.NewValue;
            }
        }