How to make horizontal stretching of elements

I don't know what to call my problem. I need to make it so that I can change the length of the elements in the horizontal "list" like this:

I did it, but in a very clumsy way. Please tell me how to do this better, for example, so that you can easily write code for several (3 or more) elements. Maybe there is some built-in JavaFX way to do this.

My code:

Main:

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) {
        Pane pane1 = new Pane();
        pane1.setPrefWidth(100);
        pane1.setBackground(new Background(new BackgroundFill(Color.RED, CornerRadii.EMPTY, Insets.EMPTY)));
        Pane pane2 = new Pane();
        HBox.setHgrow(pane2, Priority.ALWAYS);
        pane2.setBackground(new Background(new BackgroundFill(Color.GREEN, CornerRadii.EMPTY, Insets.EMPTY)));
        MainPane root = new MainPane(pane1, pane2);
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }


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

MainPane:

public final class MainPane extends HBox {

    private double mx;

    public MainPane(Pane pane1, Pane pane2) {
        getChildren().addAll(pane1, pane2);
        setOnMouseMoved(mouseEvent -> {
            if (mouseEvent.getSceneX() < pane1.getWidth() + 9 && mouseEvent.getSceneX() > (pane1.getWidth() - 6)) {
                if (getCursor() != Cursor.H_RESIZE)
                    setCursor(Cursor.H_RESIZE);
            } else if (getCursor() != Cursor.DEFAULT)
                setCursor(Cursor.DEFAULT);
        });
        setOnMouseReleased(mouseEvent -> {
            if (getCursor() == Cursor.H_RESIZE && !(mouseEvent.getSceneX() < pane1.getWidth() + 9 && mouseEvent.getSceneX() > (pane1.getWidth() - 6)))
                setCursor(Cursor.DEFAULT);
        });
        setOnMousePressed(mouseEvent -> {
            if (getCursor() == Cursor.H_RESIZE)
                mx = mouseEvent.getSceneX() - (pane1.getWidth());
        });
        setOnMouseDragged(mouseEvent -> {
            if (getCursor() == Cursor.H_RESIZE) {
                double newPane1Width = mouseEvent.getSceneX() - mx;
                double newPane2Width = pane2.getWidth() - newPane1Width + pane1.getWidth();
                pane1.setPrefWidth(newPane1Width);
                pane2.setPrefWidth(newPane2Width);
            }
        });
    }
}