I've installed the latest version of KatMouse mostly for the ability to scroll the window under the cursor (as opposed to the window with keyboard focus) with the scroll wheel on my basic wired Logitech mouse. It works very well except when I have a narrow window that can scroll both vertically and horizontally. When I scroll a window like that, the first "notch" of the scroll wheel scrolls the window sideways once. Then it scrolls down as usual.
Is this a bug or a feature? Either way, how can I get around it?
I believe this only happens in a Google Chrome window that's "snapped" to the side of the screen and zoomed out a little, but not so much that the whole page fits in the window. The only way I've been able to produce this behavior is on the edit page of any Stack Exchange network question. It's very bizarre.
(It just happened when I finished writing that update and went to scroll down to the "Save Edits" button!)
I uninstalled KatMouse and this stopped happening. I reinstalled KatMouse and now it's happening again. So KatMouse is definitely the culprit.