static KeyListener ctrlLetterKeyListener(char letter, Runnable action) {
  ret new KeyAdapter {
    public void keyReleased(KeyEvent ke) {
      if (ke.getKeyCode() == charToKeyCode(letter) && ke.getModifiers() == KeyEvent.CTRL_MASK) {
        pcallF(action);
      }
    }
  };
}

Began life as a copy of #1035314