In Firefox use wheel instead of DOMMouseScroll event.

DOMMouseScroll is non standard anymore (https://developer.mozilla.org/en-US/docs/DOM/DOM_event_reference/DOMMouseScroll). It fixes scrolling issues with trackpad in Firefox.

People reported to me that they had issues on MacOS X using Firefox when using trackpad to scroll between pages. I could reproduce. On MDN they announce that DOMMouseScroll is non-standard anymore and it has to be replaced by wheel event.

I tested it on MacBook Air with MacOS X 10.9.1 and Firefox 27.0.1. It works as expected for the people who reported the problem and myself after this fix.