See program below. I cannot get it render a node as Selected (the text should change to "Sel: " + text).

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Callback;

public class JavaFXApplication4 extends Application {

  public static void main(String[] args) {
    Application.launch(args);
  }

  @Override
  public void start(Stage primaryStage) {
    VBox root = new VBox();
    Scene scene = new Scene(root, 500, 300);
    root.getChildren().add(makeHelpTopicsTree());
    primaryStage.setScene(scene);
    primaryStage.show();
  }

  public TreeView<String> makeHelpTopicsTree() {
    TreeItem<String> root = new TreeItem<>("Root Node");
    root.setExpanded(true);

    TreeItem<String> node1 = new TreeItem<>("Tree Node 1");
    TreeItem<String> node2 = new TreeItem<>("Tree Node 2");

    TreeItem<String> node3 = new TreeItem<>("Tree Node 3");
    node3.setExpanded(true);
    TreeItem<String> node4 = new TreeItem<>("Tree Node 4");
    TreeItem<String> node5 = new TreeItem<>("Tree Node 5");
    node3.getChildren().addAll(node4, node5);
    root.getChildren().addAll(node1, node2, node3);

    treeViewHelp = new TreeView<>(root);
    treeViewHelp.setCellFactory(new Callback<TreeView<String>, TreeCell<String>>() {
      @Override
      public TreeCell<String> call(TreeView<String> treeViewHelp) {
        return new MyTreeCell();
      }
    });

    treeViewHelp.getSelectionModel().select(node4);

    return treeViewHelp;
  }

  public class MyTreeCell extends TreeCell<String> {
    @Override
    public void updateItem(String text, boolean empty) {
      super.updateItem(text, empty);

      if(!empty) {
        setText(isSelected() ? "Sel: " + text : text);
      }
    }
  }

  private TreeView<String> treeViewHelp;
}