code: @Override
    public void layoutParts() {
      // but always add the categoryController
      contentBox.getChildren().addAll(breadCrumbView, categoryController);
      VBox.setVgrow(categoryController, Priority.ALWAYS);
  
      if (!model.isOneCategoryLayout()) {
        preferencesPane.setDetailSide(Side.LEFT);
        preferencesPane.setDetailNode(navigationView);
        preferencesPane.setMasterNode(contentBox);
        setCenter(preferencesPane);
      } else {
        setCenter(new StackPane(contentBox));
      }
    }
docs: {@inheritDoc}