How to reproduce the bug:

1. Create a quiz.
2. Set the "Browser security" to "Full screen pop-up with some JavaScript security"
3. add some questions to the quiz (so students see the page with a vertical scroll bar).
4. Using Google Chrome, try to attempt the quiz using a student account. Do not preview the quiz as that does not reproduce the bug.
5. As you see the student can not use the scroll bar as it is freezed.

This works fine with Firefox, but Google Chrome seems to have problem.
My Google Chrome version is 35.0.1916.153
OS: Fedora 20