So it is not possible to deactivate messaging between students, register in course "A" to take quiz "Q", during this quiz "Q" on Moodle right ?
We have exactly the same situation.
We do not want to block messaging for entire site. But based on quiz and questionair we'd like to restrict internal messaging for participants. Full screen window is also not an option as students have to use third party softwares.
If you have any suggestion, trick or workaround, I'd really appreciate it.