public ConfigurationsDialogBuilder addOkButton() {
    dialog.okButton = new Button("OK");
    dialog.okButton.setPrefWidth(BUTTON_WIDTH * 2);
    dialog.okButton.setOnAction(
        new EventHandler<ActionEvent>() {
          public void handle(ActionEvent t) {
            dialog.chosenConfiguration = getChosenConfiguration();
            dependencyDotFileGenerator.generateOutputForConfigurations(
                preferences, dialog.chosenConfiguration, outputFileName, os);
          }
        });
    dialog.buttonsPanel.getChildren().add(dialog.okButton);

    return this;
  }