I would like to be able to modify scrolling behavior in all applicable apps on my system via an installable app or extension. I am wondering where to start. It appears an action extension would be appropriate, but I could be overlooking something. I would also want to create some kind of pref pane or menu bar control panel to allow altering the default settings. If anyone can point me at a open source example of an action extension, then I would be able to study it as an example. Pros and cons of any suggested methods would be very much appreciated.
You may want to explore the GlobalDomain of the defaults. Do a search on how to dump all the defaults in terminal to see what is available--maybe there is something for scrolling behavior you can change.