*sneaks in to say...*
Exactly the same problem as Steve with FF3, which I just loaded: Small reading frame in the upper left quadrant, instead of the full pane. I only ever use Compact mode, but I just checked Standard anyway - same deal.
On the other hand: the "reload and "earlier" buttons finally appear in the bottom outer frame. And there's nothing at all wrong with the "Reply to" pop-up, although the text in the buttons, and in the Subject and Name fields, are smaller than they were.