To reproduce open any menu.

import com.sun.javafx.runtime.VersionInfo;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class MenuBarApp extends Application {

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

    @Override
    public void start(Stage stage) throws Exception {
        stage.setTitle(VersionInfo.getRuntimeVersion());
        stage.setScene(createScene());
        stage.show();
    }

    private Scene createScene() {

        Menu file = new Menu("File");
        file.getItems().add(new MenuItem("New"));
        file.getItems().add(new MenuItem("Open"));

        Menu edit = new Menu("Edit");
        edit.getItems().add(new MenuItem("Copy"));
        edit.getItems().add(new MenuItem("Paste"));

        MenuBar menuBar = new MenuBar();
        for (int i = 0; i < 3; i++) {
            Menu menu = new Menu("Menu " + i);
            menuBar.getMenus().add(menu);
            for (int j = 0; j < 5; j++) {
                MenuItem menuItem = new MenuItem("Menu item " + j);
                menu.getItems().add(menuItem);
            }
        }

        menuBar.getMenus().add(file);
        menuBar.getMenus().add(edit);

        VBox root = new VBox(5);
        root.getChildren().add(menuBar);

        return new Scene(root, 1200, 800);
    }
}