In the comment text editor for the "Make comment or override grade" window for a quiz, the text editor for the comment gets cut off with the default window size (it does appear when you resize the window.

As I found this in the Mount Orange School Demo Moodle site, I am not sure exactly what versions of Moodle this applies to, so I just chose 2.6, which is what the Mount Orange School Demo Moodle site says is the version of Moodle it is running.