A teacher at our university has highlighted an issue that I think could be something to consider when it comes to future features for the GradeBook and/or SpeedGrader:
"When grading and a student submits a new comment or file, the notification by mail arrives as it should. However, the submission in the GUI is not marked as untreated/needs to be graded. So nothing appears on the right under the heading "To do" where I do think this should be listed. If I manually go to SpeedGrader, the students who have updated their submission with comment / attachments are not marked with the orange circle in the drop-down list at the top right. Even if I select the right student manually, the option "Use same rating for re-submission" is not displayed. (Because the new comments have not marked the submission as "re-submitted."
This is not a bug since everything works as intended, but it would be good for teachers to be alerted about this type of updates from students also in the GUI of Canvas.