This prevents the host cursor from moving into another window in capture
mode, solving the problem of input going to an overlapping window in
capture mode, and also preventing loss of focus with focus_follows_mouse.
Currently, (un)grabPointer is used both for tracking/confining the mouse
in normal mode, as well as entering/exiting capture mode. This makes it
impossible to use separate cursor logic for capture mode, which is needed
to deal with overlapping windows for the Wayland backend.
This commit creates separate (un)capturePointer for entering/exiting
capture mode. There should be no behaviour changes.
The Wayland display server is getting unwieldy due to the sheer size.
To make it easier to edit in the future, I split it into many components
based on logical boundaries.