pub fn create_pointer_barrier<'c, 'input, Conn>(
    conn: &'c Conn,
    barrier: Barrier,
    window: Window,
    x1: u16,
    y1: u16,
    x2: u16,
    y2: u16,
    directions: BarrierDirections,
    devices: &'input [u16]
) -> Result<VoidCookie<'c, Conn>, ConnectionError>
where Conn: RequestConnection + ?Sized,