Capture focus in Grader

In a site with a course, and users enrolled in it:

1. Login as teacher
2. Create a forum with whole-forum grading enabled
3. Login as a student, and post a discussion in the forum
4. Log back in as teacher
5. Navigate to the forum
6. Press Grade users
7. Use the tab, shift + tab keys, and any other means you can do attempt to focus outside of the grader
   1. Confirm that you are thwarted
8. Close the Grader
   1. Confirm that your focus was returned to the "Grade users" button
9. Re-open the grader without refreshing the page
   1. confirm that the focus lock still works no matter how many times you open/close the grader
10. With the grader open, navigate to the grading of the student who posted in step 3. Click the "View discussion" link

1. 1. Confirm that the focus lock is constrained to the discussion modal
2. Press escape/Cancel/X (all should work)
   1. Confirm that focus has been set to the "View discussion" link which you clicked to open the discussion
3. Use the tab, shift + tab keys, and any other means you can do attempt to focus outside of the grader
   1. Confirm that you are still thwarted
4. Log in as a student
5. View the forum
6. Click the "View grade" button
7. Use the tab, shift + tab keys, and any other means you can do attempt to focus outside of the grader
   1. Confirm that you are thwarted
   2. Confirm that the page does not move up/down as you tab and shift tab round in circles