// Call this AFTER other action listeners have been registered.

static void addHistoryToTextField(final JTextField input) {

  final Var<Int> historyIdx = new Var(0);

  final new L<S> history;

  input.addKeyListener(new KeyAdapter {

    public void keyPressed(KeyEvent e) {

      if (e.getKeyCode() == KeyEvent.VK_UP) {

        //print("up");

        listSet(history, historyIdx.get(), input.getText(), "");

        historyIdx.set(max(0, historyIdx.get()-1));

        S text = get(history, historyIdx.get());

        if (text != null) {

          input.setText(text);

          input.selectAll();

        }

      }

      if (e.getKeyCode() == KeyEvent.VK_DOWN) {

        //print("down");

        S text = input.getText();

        if (historyIdx.get() < l(history) ||

          neq(last(history), text))

          listSet(history, historyIdx.get(), text, "");

        historyIdx.set(min(l(history), historyIdx.get()+1));

        text = get(history, historyIdx.get());

        input.setText(unnull(text));

        input.selectAll();

      }

    }

  });

  input.addActionListener(actionListener {

    S text = input.getText();

    //print("Text: " + text);

    while (history.contains("")) history.remove("");

    history.remove(text);

    history.add(text);

    historyIdx.set(l(history));

  });

}