alpha - yeah, I see what you mean. If I just look at email in the preview window the ribbon stays down. But if I open it in a new window it's there. Wonder if that's a bug.
EDIT- In Word, when you open a second window the ribbon does stay down in that one, if you had it down in the first one. Same with OneNote. I don't know if MS is taking feedback here, or how they are, or if they even care, but I'd drop them a line.