JavaFX Application is not AlwaysOnTop of all Win-Windows

Hi,

I've used this feature on a small utility window that was a secondary Stage, but haven't on the primaryStage yet.  This following program is working for me on Ubuntu.  I'm not sure why I can't make the setAlwaysOnTop() call from within primaryStage.setOnShown().

-Carl

public class zt extends Application {

    @Override

    public void start(Stage primaryStage) throws Exception {

        Button b = new Button("Dialog");

        b.setOnAction( (evt) -> showDialog(primaryStage) );

        VBox vbox = new VBox();

        vbox.getChildren().add( b );

        Scene scene = new Scene( vbox );

        primaryStage.setScene( scene );

        primaryStage.setWidth( 1024 );

        primaryStage.setHeight( 768 );

        primaryStage.show();

    }

    public static void main(String[] args) {

        launch(args);

    }

    private void showDialog(Stage primaryStage) {

        Label label = new Label("Dialog");

        VBox vbox = new VBox();

        vbox.getChildren().add( label );

        Scene scene = new Scene( vbox );

        Stage stage = new Stage();

        stage.setScene( scene );

        stage.setWidth( 667 );

        stage.setHeight( 375 );

        primaryStage.setAlwaysOnTop(true);

        stage.setAlwaysOnTop(true);

        stage.show();

    }

}