by Paul Nicholls.
Glad I could help point you in the right direction - sorry I can't offer you an actual solution (other than "don't use Safari")! Although I'm not sure if there's actually anything that can be done to properly resolve the issue, it'd be a good idea to file a ticket on the Moodle Tracker (and list MDL-39190 as related) - that way, at least there's a solid record of the specific issue for other people to find. Naturally, if you do find a better way to deal with it than simply telling people to use a different browser, please then provide details on the ticket and/or here in the forums