public void removeCategory(final String category) {
        if (!categorizedImageListHelper.containsCategory(category)) {
            return;
        }

        changeImageCount(-categorizedImageListHelper.getCategoryCount(category));
        final int titlePos = categorizedImageListHelper.getCategoryTitlePosition(category);
        for (int pos = categorizedImageListHelper.getCategoryInsertPosition(category) - 1; pos >= titlePos; pos--) {
            adapter.removeItem(pos);
        }
        categorizedImageListHelper.removeCategory(category);
    }
registers the activity associated with this gallery for image transtions towards image detail view
main/src/main/java/cgeo/geocaching/ui/ImageGalleryView.java