`mouse_follows_focus` improvement suggestions

Hello folks, still loving Yabai. =D

I've had to re-enable SIP and so I'm learning how to work with that. One of the biggest helps for me is mouse-follows-focus. Without this, using `yabai` to change which external display is focused doesn't work. But if I use mouse-follows-focus along with focus-follows-mouse, it works great.

However, this has caused me to care a lot about mouse-follows-focus. I have one specific issues that causes me ... a lot of difficulty: focusing Finder when my mouse moves over the gap around windows. This is especially true when moving to the menubar. With focus-follows-mouse this isn't *too* bad. But with mouse-follows-focus, the mouse can be snapped to the center of the window when it drifts over the border. This is very surprising, and compounds issues.

I thought of a few improvements that would really help me, and wonder if they would be feasible.

1. Avoid changing focus when the mouse is over the desktop. I guess this is properly about focus-follows-mouse, but thought I'd mention it.
2. Avoid focus change (in any direction) when the mouse is within the padding of the window. The goal would be both to avoid de-focusing the window, but as or more important to not re-focus it and center the mouse within the window.
3. Maybe even more awesome than (2) would be to remember the location of the mouse within a window when it loses focus and rather than snapping to the *center* of the window, snap to previous location of the mouse within the window. This would be amazing for me as it would let me leave my mouse in a predictable place (maybe a button) and it still be there even after switching windows.
- Maybe a combination of (2) and (3) would be even better. When focusing a window due to focus-follows-mouse, don't change the mouse position at all. Only do mouse-follows-focus when the focusing event isn't due to following the mouse. And then do (3). This would let you move the mouse out of a window and back, and it would never snap to a different location. But when switching focus through key bindings or some non-mouse event, can restore the previous mouse location within the window.

What do you think?

Also happy to provide any more details useful.

Start by tracing the existing mouse-follows-focus and focus-follows-mouse behavior described in the issue. Compare the requested desktop, window-padding, and remembered-pointer-location cases, then define a focused scope and acceptance criteria before making changes.

Written by the indexing model from the issue text.