static <A extends Window> A onWindowDeiconified(A w, Runnable r) {
  if (w != null && r != null) swing {
    w.addWindowListener(new WindowAdapter {
      public void windowDeiconified(WindowEvent e) {
        pcall { r.run(); }
      }
    });
  }
  ret w;
}

Began life as a copy of #1016868