Thanks for the feedback, folks! Clearly the drag-image-to-scroll thing I hacked in before going off to a drunken Smash Brothers tournament/general party didn’t work. It’s back to where it was before.
I’m sort of toying with the idea of overlaying a ‘move back a page’ link on the left side of each page on the chapter view. Dunno. I’m sure people who Only Use Mousewheels will still hate it, but whatevs – a script to turn u/d wheeling into l/r movement seriously fucks with scrolling around via the Mac’s trackpad, which is how I navigate when I’m on my laptop. I got book-printing stuff to take care of first today.