Code Added to Color Scheme for Completed Grading of an Assignment

Perhaps I am too Type-A, but I would like to see when I have an entire assignment graded for a class since students sometimes submit work at different times, and I grade it at different times.  Instead of scrolling through each column from top to bottom to check that I have not missed anything late work submitted, it would be nice if I could "check off" that I am done with that assignment as far as grading.  Yes, I know I can check the "Needs to Be Graded," but I like to see it in the grade spread sheet as well.

Thank you!