Issue
Context change - When the user selects a repository on the left hand side of the Add... modal in the file picker the focus is not placed on the right hand side it is still on the selected repository name and the user has to tab through all the rest of the repositories to get to the right hand side.
Guidance - Modal window is not being announced at all to screen reader users.

Standard Level
WCAG 2 3.2.2 (A) http://www.w3.org/WAI/WCAG20/quickref/#qr-minimize-error-cues
WCAG 2 4.1.2 (A) http://www.w3.org/WAI/WCAG20/quickref/#qr-ensure-compat-rsv

Impact
Critical

Example Link
http://demo.moodle.net/mod/assign/view.php?id=1778&action=editsubmission

Test Steps

1. Login as a student
2. Navigate to a course
3. Click the assignment
4. Click add submissions
5. Click the add... button
6. Click the Private files button in the file picker with a screen reader.
7. Notice the screen reader starts reading at the next repository not the refresh icon.