static <A extends JComponent> A onCharDown(final VF1<Char> onCharDown, final A a) {
  if (a != null) swing {
    a.addKeyListener(new KeyAdapter {
      @Override
      public void keyTyped(KeyEvent e) {
        if (e.getModifiers() == 0)
          pcallF(onCharDown, e.getKeyChar());
      }
    });
  }
  ret a;
}

static <A extends JComponent> A onCharDown(A a, VF1<Char> onCharDown) {
  ret onCharDown(onCharDown, a);
}