I was hoping that I could use an roScreen as a part of a menu stack of roParagraphScreens/roPosterScreens, and be able to place a roSpringBoardScreen occasionally on top for user interaction. In my use case, I would expect the roScreen to completely obscure what is under it and it would be completely obscured by what was on top of it. That way, you could choose roImageCanvas or roScreen as needed and still maintain a menu stack.
Based on the comment in the manual, this would not be officially supported. If there is another official stance, I'd love to hear it 🙂
