A toggle to turn off/on cycling thru books via right-arrow and left-arrow.
I have accidentally changed the book I was reading by pressing right-arrow or left-arrow. On my 2-monitor system, I sometimes do not recognize which program has focus because so many "modern" program UIs are monochrome mush or after being called away from the computer. It is disconcerting when it happens. I never intentionally use this feature. So I'd like to disable it on my system.