• Pane VS. StackPane Compared;
  

• StackPane lays out its children in a back-to-front stack
•  When an application needs children to be kept aligned within a parent (centered, positioned at top-left, etc), it should use a StackPane instead of Pane Base class.

package javafxtemplate2;

import javafx.application.Application;
import javafx.scene.*;
import javafx.scene.control.Label;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

/**
 *
 * @author Manas9
 */
public class JavaFXTemplate2 extends Application {
     @Override
    public void start(Stage primaryStage) {
     Rectangle rect = new Rectangle(25, 25, 50, 50);
     rect.setFill(Color.CADETBLUE);
     Label caption = new Label("Label1"); 
     caption.setTranslateX(10);caption.setTranslateY(20);
     Line line = new Line(90, 40, 230, 40);
     line.setStroke(Color.BLACK);
     Circle circle = new Circle(130, 130, 30);
     circle.setFill(Color.CHOCOLATE);
     Pane proot = new Pane(); 
        //StackPane proot = new StackPane(); 
    proot.getChildren()
    .addAll(caption,rect, line, circle);
    Scene scene = new Scene
    (proot, 250, 220, Color.WHITESMOKE);
    primaryStage.setTitle
    ("Absolute layout");
  // primaryStage.setTitle
  //("Stack Overrides Absolute layout");
     primaryStage.setScene(scene);
      primaryStage.show();
}
     public static void main(String[] args) {
        launch(args);
    }
  
}

Pane proot = new Pane();
        //StackPane proot = new StackPane();
    proot.getChildren()
    .addAll(caption,rect, line, circle);

Runtime as StackPane:

//Pane proot = new Pane();
    StackPane proot = new StackPane();
    proot.getChildren().addAll(caption,rect, line, circle);