sclass JThumbnailButton > JButton {
  ThumbnailCache thumbnailCache;
  File imageFile;
  
  *(ThumbnailCache *thumbnailCache, File *imageFile) {
    setButtonImage(this, whiteImage(thumbnailCache.thumbnailSize()));
    thumbnailCache.get(imageFile, img -> {
      BufferedImage canvas = whiteImage(thumbnailCache.thumbnailSize());
      drawImageOnImage(img, canvas);
      setButtonImage(this, canvas);
    });
  }
}