@FXML
  void showFileChooser() {
    FileChooser fileChooser = new FileChooser();
    fileChooser.setInitialFileName("export");
    fileChooser.setSelectedExtensionFilter(
        new FileChooser.ExtensionFilter("export to excel", ".xlsx"));

    File file = fileChooser.showOpenDialog(exportBtn.getScene().getWindow());
    exportFile.set(file);
  }
  @FXML
  private void sendRound() {
    if (answerForQuestion.size() != currentPlayingRound.get().getAmountOfQuestions()) {
      messageMaker.showWarning("niet alle vragen zijn ingevuld");
      return;
    }

    send(questionsForRound.get(currentPlayingRound.get()));

    // de huidige ronde verwijderen
    questionsForRound.remove(currentPlayingRound.get());
    if (questionsForRound.isEmpty()) {
      currentPlayingRound.set(null);
    } else {
      for (RoundSubmit s : questionsForRound.keySet()) {
        currentPlayingRound.set(s);
        break;
      }
    }
  }
 private void update(Wallet wallet) {
   balance.set(wallet.getBalance());
   address.set(wallet.currentReceiveAddress());
 }