I've been looking at https://github.com/rokudev/scenegraph-master-sample and followed the screenStack UI Logic. I initialise the screenStack on MainScene.brs and show my Login screen. After the user logs in, I want to navigate the user to the Home Screen but I'm unable to do so because when I call ShowScreen inside Login.brs, the screenStack is not initialised, even though I did that on my MainScene.brs. Is there a way to change Screens(Groups) from the Login Group itself?