How to switch scenes in JavaFX

Instead of switching Scenes, switch a root node on already existing Scene

I wrote this controller to keep track of the different scenegraphes.

public class ScreenController {
    private HashMap<String, Pane> screenMap = new HashMap<>();
    private Scene main;

    public ScreenController(Scene main) {
        this.main = main;
    }

    protected void addScreen(String name, Pane pane){
         screenMap.put(name, pane);
    }

    protected void removeScreen(String name){
        screenMap.remove(name);
    }

    protected void activate(String name){
        main.setRoot( screenMap.get(name) );
    }
}

So I can write:

ScreenController screenController = new ScreenController(scene);
screenController.add("calculator", FXMLLoader.load(getClass().getResource( "calculator.fxml" )));
screenController.add("testSwitch", FXMLLoader.load(getClass().getResource( "TestSwitch.fxml" )));
screenController.activate("calculator");

This was a workaround for a fullscreen application, where the MacOS fullscreen transition was shown every time a stage switches its scene.