public static void selectTheme(@NonNull final Activity activity, @NonNull final GoogleMap map, @Nullable final ScaleDrawer scaleDrawer) {
        final SimpleDialog.ItemSelectModel<GoogleMapsTheme> model = new SimpleDialog.ItemSelectModel<>();
        model
            .setItems(Arrays.asList(GoogleMapsTheme.values()))
            .setDisplayMapper((l) -> TextParam.text(l.getLabel()))
            .setChoiceMode(SimpleItemListModel.ChoiceMode.SINGLE_RADIO)
            .setSelectedItems(Collections.singleton(GoogleMapsTheme.getCurrent()));

        SimpleDialog.of(activity).setTitle(R.string.map_theme_select).selectSingle(model, theme -> {
            GoogleMapsTheme.setCurrent(theme);
            setCurrentThemeOnMap(map, scaleDrawer);
        });
    }
Open theme selection dialog for GM map view, store result in settings and applies it to map
main/src/main/java/cgeo/geocaching/unifiedmap/googlemaps/GoogleMapsThemeHelper.java