Function ncplane_move_above 

pub unsafe extern "C" fn ncplane_move_above(
    n: *mut ncplane,
    above: *mut ncplane,
) -> c_int

Splice ncplane ‘n’ out of the z-buffer, and reinsert it above ‘above’. Returns non-zero if ‘n’ is already in the desired location. ‘n’ and ‘above’ must not be the same plane. If ‘above’ is NULL, ‘n’ is moved to the bottom of its pile.