In the old gradebook, an "on hover" event caused a comment icon to appear in the top-right corner of a gradebook cell. This was a good visual cue to indicate that additional functionality could be accessed via a click.
No "on hover" event is present in the New Gradebook. Rather, a user must click the cell to access the visual cue / button for loading the side tray.
It would be great to have the box-with-arrow icon appear upon hovering in a cell in the New Gradebook.