Ability to show groups in GradeBook

As a teacher I need an easy way to view only my groups so I know that I am reviewing the correct group

What is the current scenario?
Add a filter on GB to work like assignment where you can select a subset and have full access to all the usual features but limited to that subset.
Courses can have multiple groups with different teachers and each teacher wants to only see their own group when grading.
It's partly a documentation/ usabilty issue.