Using: Moodle 3.1.1+ (Build 20160804) and Essential 126.96.36.199 (Build: 2016061703)
Looking at an assignment to grade, the annotation bar with the stamps / comments interface on it is wacky. Not there at some resolutions, half there in others, as I scale the window. I think it might be a css issue, but I'm not great with css.
I've confirmed that it behaves as expected with a dynamically scaling bar if I switch to More or Clean.