Steps to reproduce:
1. Open PDF editing of a submitted assignment.
2. Create a comment and start typing.
EACH character typed will increase the height of the comment for a few pixels below.
This happens on all keypressed events, including deleting characters, or just moving with arrows.
3. Move to the next page, then return to the original page.
4. The comment is now back to normal size.

I'm having this problem only on Chrome, Firefox is OK.