ListView's scroll bar does not appear if items are added to the ObserverableList(containing the ListView's items) one by one

Below codes can be used to re-produce

How to re-produce:

1. Run the sample
2. Click <Go> button, you will see items are added to the ListView one by one and
    soon will see the number of the added items exceeds the number of items that
    can be displayed in the viewport of the ListView, but no scroll bar appears


-----------
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package largelistviewissue;

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;

/**
 *
 * @author lianqi.li
 */
public class LargeListViewIssue extends Application {
    java.util.List<java.lang.String> fontNames = Font.getFontNames();
    ObservableList<java.lang.String> listItems = FXCollections.observableArrayList();
    Service s = null;

    @Override public void start(Stage stage) {
        stage.setTitle("TableView Issue");
        final Group root = new Group();
        final Scene scene = new Scene(root, 500, 400);

        final ListView<String> listView = new ListView<String>();
        listView.setTranslateX(10);
        listView.setTranslateY(10);
        listView.setPrefHeight(240);
        final Text t = new Text(10, 280, "");
        
        final Button bGo = new Button("Go");
        bGo.setLayoutX(10);
        bGo.setLayoutY(300);
        bGo.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                listView.getItems().clear();

                s = new Service() {
                    @Override protected Task createTask() {
                        return new Task() {
                            @Override public Void call() throws Exception {
                                for(int i = 0; i < fontNames.size(); i++) {
                                    try {
                                        Thread.sleep(1000);
                                        listItems.add(fontNames.get(i));
                                        t.setText("" + listView.getItems().size() + " font names added");
                                    } catch(java.lang.Exception e) {}
                                }
                                return null;
                            }
                        };
                    }
                };

                listView.setItems(listItems);
                t.setText("" + listView.getItems().size() + " font names added");

                s.start();
            }
        });

        final Button bCancel = new Button("Cancel");
        bCancel.setLayoutX(100);
        bCancel.setLayoutY(300);
        bCancel.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                s.cancel();
            }
        });

        root.getChildren().addAll(listView, t, bGo, bCancel);

        stage.setScene(scene);
        stage.show();
    }

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