Focus-follows-mouse is sorely needed, at least as an option, in OSX.
I used to achieve FFM, circa snow-leopard, with the excellent "mondomouse" from AtomicBird, but it is no longer maintained and will not work with modern OSX versions.
Looking ahead, it appears that there is some new capability buried deep inside the accessibility section of Preferences that actually enables FFM, but I do not have a new enough (Mojave ?) version of OSX to verify this ...
EDIT: I think it is actually High Sierra that this new accessibility feature appeared in, but again, not sure ...
I used to achieve FFM, circa snow-leopard, with the excellent "mondomouse" from AtomicBird, but it is no longer maintained and will not work with modern OSX versions.
Looking ahead, it appears that there is some new capability buried deep inside the accessibility section of Preferences that actually enables FFM, but I do not have a new enough (Mojave ?) version of OSX to verify this ...
EDIT: I think it is actually High Sierra that this new accessibility feature appeared in, but again, not sure ...