I am having an issue when trying to annotate assignment submissions. The attached picture shows what I see instead of the normal tool bar. The remainder of the tool bar is available if I use the miniature scroll bar next to the stamp tool, and all of the hidden tools work as expected. The stamp tool does not work at all. Pressing either of the key combinations listed next to the stamp tool does nothing.
I had this same issue with 3.3.1 as well. This problem is not theme-dependent.
Any ideas how to fix this?