I just happened to start using it while the lower frame was as close to the top as possible, and finally it appeared! What happens is the font thing seems to be separate from the actual field.
It's really messy, I think, that they don't work in sync. Web Designers for Obama/Biden 08.
The worst manifestation of this bug appears only on Mozilla browsers. The main window must be scrolled to the top in order for the font menu to appear in the right place (or at all). For a forum that claims to support FireFox, this is a pretty major bug, IMHO (and one that was noted long ago).
On IE the menu initially appears in the right place, but scrolls with the main window.
Actually, the number of bugs and usability issues in the composition window is quite large. A complete rewrite would be in order, IMHO.