Currently, when an assignment is set to the Manual grade posting policy, there is no indication in SpeedGrader that anything is hidden from students until a grade is posted. So for instructors like me, who may post comments, mark up submissions, or partially fill out rubrics before assigning a grade, if we click the little eye icon, this is what we see:
The Manual policy is supposed to hide comments, rubrics, etc. from students until we manually post them, but as an instructor, when I see this signal, it looks like nothing will be hidden until a grade is entered. I would be much more confident if (a) the eye had a slash through it, and (b) the message was something like "Grading in Progress," so I knew students wouldn't be able to see the work I'm currently doing.