Here's a handy tip for sizing your application. You can use the javafx.stage.Screen class to obtain the width and height of the user's screen, and then use those same dimensions when sizing your scene. The following code modifies default "Hello World" application that appears when you create a new JavaFX project in NetBeans.

package screendemo;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.stage.Stage;
import javafx.stage.Screen;
import javafx.geometry.Rectangle2D;

public class ScreenDemo extends Application {

    public static void main(String[] args) {
        Application.launch(args);
    }
    
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Hello World");
        Group root = new Group();
        Rectangle2D screenBounds = Screen.getPrimary().getVisualBounds();
        Scene scene = new Scene(root, screenBounds.getWidth(), screenBounds.getHeight());   
        Button btn = new Button();
        btn.setLayoutX(100);
        btn.setLayoutY(80);
        btn.setText("Hello World");
        btn.setOnAction(new EventHandler() {

            public void handle(ActionEvent event) {
                System.out.println("Hello World");
            }
        });
        root.getChildren().add(btn);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}

Running this program will set the Stage boundaries to visible bounds of the main screen.

-- Scott Hommel