Filepicker and file manager view files buttons do not announce change on the page

Issue
Context changes - When the user clicks the icons in the upper right of the file picker to change the view type of the files (icons, detail and tree) the user is not informed of a change to the page. This also occurs when you are within a file repository after clicking the Add... button
Guidance - Modal window is not being announced at all to screen reader users.

Standard Level*
WCAG 2 3.3.2 (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
Serious
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 tree icon
6. Notice nothing is announced to the screen reader when the error modal appears