Hi Michael, thanks for your reply, that -debug events flag is super helpful and I’ll make sure to remember it in the future!
Unfortunately when I tried with my own Logitech mouse on my Macbook, I found that shift+scrolling would not trigger any events, although regular scrolling and all other actions did. I did some digging and found that MacOS has a (rather unadvertised) feature where using an external mouse’s scrollwheel with the shift key actually scrolls horizontally. And it appears that RV doesn’t have any events to handle this horizontal scroll action.
The reason the event works when shift+scrolling with the touchpad is because the touchpad has no such function, since after all you can just move your fingers side to side on the touchpad to horizontal scroll. So shift+scrolling on the touchpad is just registered as a regular scroll.
I’m quite stumped by this problem, as this function is for a variety of users, some of whom will be using iMac desktops which have no touchpad…