问JavaFX防止新阶段偷走primaryStage的焦点

EN

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class StageFocus extends Application {
    @Override
    public void start(Stage primaryStage) throws Exception {
        final Button button = new Button("New Stage");
        button.setOnAction(e -> {
            final Stage stage = new Stage();
            stage.setWidth(200);
            stage.setHeight(200);
            stage.setTitle("New Stage");
            stage.show();
        });
        final Scene scene = new Scene(new StackPane(button), 300, 300);
        primaryStage.focusedProperty().addListener((observable, oldValue, newValue) -> {
            if (!newValue) {
                primaryStage.requestFocus();
            }
        });
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}