In the Assignment grading page, "Submission comments" expand when you click on the link that says "Comments (3)". Due to the limited space in the gradebook a teacher will often want to view the FirstName/Surname column, grade column and submission comments columns at the same time. (I often hide the user picture, the email address and some other less important columns)

This works fine until you hide the "file submissions" column. All of a sudden the comments fail to expand until you "show" the "file submissions" column.

Replication steps:

1. Log in as teacher/admin
2. Create an assigment
3. Log in as a student
4. Submit to the assignment
5. Log in as teacher/admin
6. Navigate to the assignment's Grading page
7. Note that a submission and a link to add comments
8. Minimise the File submissions column
9. Click the link to add a comment

Expected result: The comment text box should appear

Actual result: The link is inactive