Ugh, I’m really sorry about that Scott. This has been an annoyance for us all over the years :(.
The problem is that Adobe Air’s scrolling listener doesn’t do a great job listening to horizontal scrolls. It sometimes works with some hardware, but other times it just doesn’t work at all. There isn’t really a rhyme or reason to it, which makes it all the more frustrating.
If you hold while scrolling up and down, the canvas will scroll horizontally. That’s something we added a year or so back to help mitigate this issue.
Ultimately, however, we won’t be able to fully solve this issue until we have a native (non-Adobe Air) desktop app - which will allow us to control the scrolling event handling. We have been working on moving all of our apps to native frameworks, and the desktop app is coming along nicely. We should be able to talk more about it soon.
I’m really sorry for the frustration this is causing you, Scott, and even more sorry that I don’t have a good solution for you today. Hopefully it won’t be an issue for too much longer.