Please see MDL-47978.

The problem was that the action menu was being used inside a relatively positioned element (an element positioned by float or absolutely).
The solution there was a quick solution for pre-release timing, however a better solution should be found to implement a property for the action menu to state that its values should not wrap.
Then style the property so that items don't wrap and remove the quiz hack.

This way when we encounter this sort of problem in the future we can just flick a switch and it is fixed.