[feature request] lock mouse in a rectangle

[CaptainTux]

first of all, great package, fits my use case perfectly. it'd be awesome to be able to lock the mouse in a box (not sure if this would be outside the scope of this crate). Say for example I have coordinates, width and height. I want to lock the mouse in that rectangle. For example calling a function like fn lock_mouse(x: i32, y: i32, width: i32, height: i32) would lock the mouse in that rectangle. kind of an equivalent to winit's set_cursor_grab (see here) and, of course, a function to unlock it as well.