Run code:

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class TreeViewSample extends Application {

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

    @Override
    public void start(Stage primaryStage) {
        HBox hbox = baseFill(new HBox());
        hbox.setAlignment(Pos.BASELINE_CENTER);

        hbox.setTranslateX(10);
        hbox.setTranslateY(10);

        StackPane root = new StackPane();
        root.getChildren().add(hbox);
        primaryStage.setScene(new Scene(root, 400, 400));
        primaryStage.show();
    }

    protected HBox baseFill(HBox hbox) {
        hbox.getChildren().add(new ProgressBar());
        hbox.getChildren().add(new ProgressBar());
        hbox.setPrefSize(270, 270);
        hbox.setFillHeight(false);
        return hbox;
    }
}

If you resize scene, two controls will jump.