Focus modal box upon initialization

Review Request #10992 — Created April 7, 2020 and submitted — Latest diff uploaded

Information

Djblets
release-1.0.x
f42d27a...

Reviewers

This change makes the modal box focusable by adding the
attribute tabindex="0" to the element and calling focus on it
when it is initialized. This allows views that have modalBox
as a parent to detect key events within it, such as RB.DialogView.

Manual verification that the modal box is focused when it is
created in the new review request dialog and the file upload
dialog. This is indicated by the focus ring around the dialogs
in the attached screenshots.