Attendance by Roll Group: checkbox to hide confidential data

As our teachers are now using Rollgroup Attendance, they are requesting for the same checkbox that you see in other places, to hide the confidential data.
This is the file I am talking about: /modules/Attendance/attendance_take_byRollGroup.php

Additionally, they are asking about having that checkbox state either remembered per user, or on by default. Our students love to peek over their shoulders, I guess?

Urko, sorry, I never got the notification for this post. Things are pretty much tied down for v14 right now, with the release imminent. Perhaps this is one feature you might consider contributing to v15? I know those skills are in there!