Hi Joseph,
I'm a low vision user having a magnifier at 6-8x to be able to use a computer.
Locking mouse, caret and focus tracking into a single mode is not something that I would appreciate. The best combination of tracking modes depends on the application you're using.
The combination of settings that works well in most applications for me is:
mouse = relative (push)
caret = center
focus = center
ZoomText had a very simple yet powerful UI to configure tracking. It was just a grid of radio buttons. It had {mouse, caret, focus} labels on the x-axis and {center, relative, edge, none} labels on y.
Please consider this approach. It doesn't look fancy, I know, but it's the most practical way to configure tracking imho.
