Pick first focusable element in modal content
..rather than the first element of the contained <form>
. This makes the default focus in various modals considerably more reasonable and unsurprising.
(Doesn't resolve any particular issue.)
For example, before (this is the result upon selecting a file to upload and then not changing the focus):
After:
This also makes the first account be selected, rather than "turn emoticons into emoji", once !16 (merged) is merged.