Swing/ScrollBarTrackHighlightForeground のバックアップ(No.1)

JTextArea log = new JTextArea(200, 200) {
  @Override public void updateUI() {
    super.updateUI();
    EventQueue.invokeLater(() -> {
      info("ScrollBar.track");
      info("ScrollBar.trackForeground");
      info("ScrollBar.trackHighlight");
      info("ScrollBar.trackHighlightForeground");
    });
  }

  private void info(String key) {
    Color color = UIManager.getLookAndFeelDefaults().getColor(key);
    append(String.format("%s: %s%n", key, color));
  }
};
UIManager.put("ScrollBar.track", Color.GREEN);
UIManager.put("ScrollBar.trackForeground", Color.WHITE);
UIManager.put("ScrollBar.trackHighlight", Color.PINK);
UIManager.put("ScrollBar.trackHighlightForeground", Color.RED);
JScrollPane scroll = new JScrollPane(log);
add(scroll);