When viewing a student's submission and using advanced grading, we currently have the ability to make that grading criteria a separate pop-up, but this is not able to be moved as a window on the screen and covers the student's submission, which does not make it user-friendly.

I would suggest that when you click on the grading criteria to expand them, that this window is able to be moved around as a separate window, as this would also support using two screens for the grader, so that the pop-up could be moved to a separate screen and therefore not cover the student's submission.