private static void LayerChanged(DependencyObject source, DependencyPropertyChangedEventArgs eventArgs)
        {
            OpenStreetMapProvider provider = source as OpenStreetMapProvider;

            if (provider != null)
            {
                provider.OnLayerChanged((TOpenStreetMapLayer)eventArgs.NewValue);
            }
        }
        private static object LayerCoerceChanged(DependencyObject source, object baseValue)
        {
            OpenStreetMapProvider provider = source as OpenStreetMapProvider;

            if (provider != null)
            {
                provider.OnLayerChanged((TOpenStreetMapLayer)baseValue);
            }

            return((TOpenStreetMapLayer)baseValue);
        }