public VBox thirdBox() {
        Button startButton = new Button("Start");
        startButton.setOnAction(actionEvent -> {
            paused = false;
            ogld.setWorld(world);

            Thread thread = new Thread(new Runnable() {

                @Override
                public void run() {
                    Runnable updater = new Runnable() {
                        @Override
                        public void run() {
                            ogld.step();
                        }
                    };

                    while (!paused) {
                        try {
                            Thread.sleep((long) i*1000);
                        } catch (InterruptedException ex) {
                        }
                        // UI update is run on the Application thread
                        Platform.runLater(updater);
                    }
                }

            });
            // don't let thread prevent JVM shutdown
            thread.setDaemon(true);
            thread.start();

        });
        Button pause = new Button("Pause");
        pause.setOnAction(actionEvent -> {
            paused = true;
        });

        startButton.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
        pause.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
        VBox vbButtons = new VBox();
        vbButtons.setPadding(new Insets(10, 10, 10, 10));
        vbButtons.setSpacing(10);
        vbButtons.getChildren().addAll(startButton, pause);
        return vbButtons;
    }