label.setGraphic() with an ImageView does not respond to mouse clicks

When we add an onMouseClicked-Eventhandler to an ImageView and set this ImageView as an icon to a Label with the setGraphic() method, the ImageView will not respond to any mouse clicked events.

However, when we wrap the ImageView in an HBox the mouse-event works! If we use a Rectangle node in place of the ImageView mouse-events work as well (without the need to wrap in an HBox).

ImageView and Rectangle appear as regular nodes to us. So why is there a difference in mouse-event processing?

SSCCE (you'll need a "any.png" image resource in the classpath)

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ImageViewApp extends Application {
    private final Image image = new Image(ImageViewApp.class.getResourceAsStream("any.png"));

    @Override
    public void start(final Stage stage) throws Exception {
        System.out.println("java.version: " + System.getProperty("java.version"));
        System.out.println("javafx.runtime.version: " + System.getProperty("javafx.runtime.version"));

        // create a label and call setGraphic() with an ImageView node
        Label label1 = new Label("onMouseClick on icon does not work");
        label1.setGraphic(createImageView());

        // create a label and call setGraphic() with an ImageView node wrapped in an HBox node
        Label label2 = new Label("onMouseClick on icon WORKS");
        label2.setGraphic(wrapInHBox(createImageView()));

        // put everything into an VBox
        VBox vbox = new VBox();
        vbox.setPadding(new Insets(20));
        vbox.setSpacing(20);
        vbox.getChildren().addAll(label1, label2);

        stage.setScene(new Scene(vbox));
        stage.show();
    }

    private ImageView createImageView() {
        ImageView imageView = new ImageView(image);
        imageView.setOnMouseClicked(new EventHandler<MouseEvent>() {
            @Override
            public void handle(final MouseEvent mouseEvent) {
                System.out.println("CLICKED"); // will only be seen when the ImageView is wrapped in a HBox
            }
        });
        return imageView;
    }

    private Node wrapInHBox(final ImageView imageView) {
        HBox result = new HBox();
        result.getChildren().add(imageView);
        return result;
    }

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