private void showHistoryArea(Map<String, Object> state) {
    @SuppressWarnings("unchecked")
    List<String> guessHistory = (List<String>)state.get(GUESSHISTORY);
    this.historyArea.clear();
    if (guessHistory != null){
      this.historyArea.add(this.createGuessPanel(guessHistory));
    }
  }