sclass JGallery_v2 {
  JPanel panel = jpanel(new VScrollingWrapLayout);
  
  settable new ThumbnailCache thumbnailCache;
  
  void add(File imageFile) {
    if (imageFile == null) ret;
    addComponent(panel, new JThumbnailButton(thumbnailCache, imageFile));
  }
  
  void addAll(Iterable<File> imageFiles) {
    fOr (f : imageFiles) add(f);
  }
  
  L<JThumbnailButton> buttons() {
    ret childrenOfType(panel, JThumbnailButton);
  }
  
  JThumbnailButton findButton(ImageFile imageFile) {
    if (imageFile == null) null;
    ret first(buttons(), btn -> eq(btn.imageFile, imageFile));
  }
  
  cachedVisual
    jscroll_vertical(panel);
}