When taken a quiz on Chrome browser, vertical scroll slider won't work if "browser security" is set to "Full screen pop-up with some JavaScript security" on quiz properties. Neither work up/down buttons.
It works correctly in Firefox 26.0.
Mouse scroll wheel works.

Tested on Chrome 32.0.1700.77 on Ubuntu and 32.0.1700.76 on Windows 7 (on windows the up/down buttons are missing, the slider doesn't work)