* Start a compose when we do a file upload
* Restore the "Formatting" and "Feedback" links.
* Dismiss composebox error messages when we defocus composebox
Realistically, the "correct" way to do this is not to have to
explicitly manage the composebox's state, as we do now -- it should
just be 100% visible and ready to send any time you click 'send'; it
shouldn't need to have first been composebox.start()ed.
(imported from commit 7f1725c229ed968a9b5500b25d600306173182a0)