/// <summary>
        /// MaximumProperty property changed handler.
        /// </summary>
        /// <param name="d">DateTimeAxis2 that changed its Maximum.</param>
        /// <param name="e">Event arguments.</param>
        private static void OnMaximumPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            DateTimeAxis source   = (DateTimeAxis)d;
            DateTime?    newValue = (DateTime?)e.NewValue;

            source.OnMaximumPropertyChanged(newValue);
        }