Order of elements and events.

Question

INTRO
Hi Oracle community.
A while ago I started a thread here on the forum where I had put three different subjects to be treated. The user jsmith guided me saying that I was supposed to separate things, dividing each subject in a separate thread. The original discussion is at the following link:
Interesting things, however, unknown? StackPane, animations and filters.
ABOUT
So in this discussion, I will be talking about input events and maybe about event filters. I created a JavaFX 8 (b123) application that checks the mouse click on certain nodes. Basically I have a panel of buttons. Behind this panel, I have a scroll pane with rectangles. The rectangles are contained within a Group, and the buttons are in a VBox. The Group is set as ScrollPane content. VBox and ScrollPane are within a StackPane, which becomes the root of scene graph. If we observe the nodes tree, we'll find the following scenario:
IMAGE
Here is my source code:
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ScrollPane;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
public class ScrollTest extends Application
    //                                                                                                       MAIN
    public static void main(String[] args)
        Application.launch(args);
    //                                                                                                 INSTÂNCIAS
    // CONTROLS
    private Rectangle[] rectangles;
    private ScrollPane scrollP;
    private Button[] buttons;
    // LAYOUTS
    private StackPane root;
    private Group group;
    private VBox vbox;
    //                                                                                                  INÍCIO FX
    @Override public void start(Stage estagio) throws Exception
        this.iniFX();
        this.confFX();
        this.adFX();
        this.evFX();
        Scene cenario = new Scene(this.root , 640, 480);
        estagio.setScene(cenario);
        estagio.setTitle("Programa JavaFX - RDS");
        estagio.show();
    /** Just instantiate JavaFX objects.*/
    protected void iniFX()
        // CONTROLS
        this.rectangles = new Rectangle[5];
        this.scrollP = new ScrollPane();
        this.buttons = new Button[6];
        // LAYOUTS
        this.root = new StackPane();
        this.group = new Group();
        this.vbox = new VBox();
    /** Just sets the JavaFX objects.*/
    protected void confFX()
        // CONTROLS
        for(int count = 0 ; count < this.rectangles.length ; count++)
            this.rectangles[count] = new Rectangle();
            this.rectangles[count].setWidth(Math.random() * 100 + 20);
            this.rectangles[count].setHeight(Math.random() * 100 + 20);
            this.rectangles[count].setFill(Color.rgb((int) (Math.random() * 255) , (int) (Math.random() * 255) , (int) (Math.random() * 255)));
            this.rectangles[count].setTranslateX(Math.random() * 600);
            this.rectangles[count].setTranslateY(Math.random() * 600);
            this.rectangles[count].setRotate(Math.random() * 360);
        for(int count = 0 ; count < this.buttons.length ; count++)
            this.buttons[count] = new Button("Button - " + count);
        // this.scrollP.setVbarPolicy(ScrollBarPolicy.ALWAYS);
        // this.scrollP.setHbarPolicy(ScrollBarPolicy.ALWAYS);
        this.scrollP.setPrefSize(400 , 400);
        // LAYOUTS
        this.vbox.setAlignment(Pos.CENTER);
        this.vbox.setSpacing(20);
        // This doesn't solve my problem.
        // this.vbox.setMouseTransparent(true);
    /** Just create the realtion between nodes, and the root.*/
    protected void adFX()
        for(int count = 0 ; count < this.rectangles.length ; count++)
            this.group.getChildren().add(this.rectangles[count]);
        for(int count = 0 ; count < this.buttons.length ; count++)
            this.vbox.getChildren().add(this.buttons[count]);
        this.scrollP.setContent(this.group);
        this.root.getChildren().add(this.scrollP);
        this.root.getChildren().add(this.vbox);
    /** Just add some events to some nodes for debugging.*/
    protected void evFX()
        this.vbox.setOnMousePressed(new EventHandler<MouseEvent>()
            @Override public void handle(MouseEvent e)
                System.out.println("Mouse pressed inside VBox.");
        this.scrollP.setOnMousePressed(new EventHandler<MouseEvent>()
            @Override public void handle(MouseEvent e)
                System.out.println("Mouse pressed inside ScrollPane.");
        if(this.rectangles.length > 0)
            this.rectangles[0].setOnMousePressed(new EventHandler<MouseEvent>()
                @Override public void handle(MouseEvent e)
                    System.out.println("Rectangle pressed.");
                    rectangles[0].setFill(Color.rgb((int) (Math.random() * 255) , (int) (Math.random() * 255) , (int) (Math.random() * 255)));
THE PROBLEM
I wish I could click the mouse on VBox buttons, but also in the scroll pane, and in it's internal contents (the rectangles). I tried changing the VBox mouseTransparent property to true, and modify mouseTransparent to false on each VBox button, but that did not work. I've been reading the JavaFX documentation talking about routing events, and found the following:
The route can be modified as event filters and event handlers along the route process the event. Also, if an event filter or event handler consumes the event at any point, some nodes on the initial route might not receive the event.
Could it be that VBox is filtering events so they do not reach ScrollPane? Or is this being done by StackPane in some other manner? Does anyone have any idea what I could do?
In any case, I thank you for your attention.

Answer 1

You might need to modify the event dispatch tree so that the events get beyond the VBox. I'm not saying this is the right thing to do, but something worth looking at.
root.setEventDispatcher(new EventDispatcher() {
@Override
public Event dispatchEvent(Event event, EventDispatchChain tail) {
tail.append(group.getEventDispatcher());
return tail.dispatchEvent(event);
There is some info on event processing at Handling JavaFX Events: Processing Events | JavaFX 2 Tutorials and Documentation