Persist mouse position with mouse_follows_focus when app regain focus.

[yihou]

Currently, when mouse_follows_focus is enabled, switching between apps causing the mouse cursor to place at the center of the newly focused app.

The benefit when the mouse cursor's position restores when the app regains focus, reduce the need of repositioning the mouse cursor again when the app regains focus, for example I like to have my mouse cursor placed near the text field when I use Slack useful when I want to change the formatting of the text as I type.

I really like mouse_follows_focus still because it reduces the distance for me to move my mouse when i focus on 1 app from another, but when I need to switch between apps constantly, the feature making it slightly inconvenient sometimes.