This is from an earlier bug report thread ( link! ) that I have found to be most assuredly NOT resolved!! Like the posters in the linked thread, I used shift-wheel horizontal scrolling ALL the time in Roll20, and only recently discovered it wasn't working. HUGELY inconvenient!! I wish that I'd found the linked thread before it was closed and marked "resolved." Chrome Version 55.0.2883.95 Mac OS X 10.11.6