Function ncdirect_box 

pub unsafe extern "C" fn ncdirect_box(
    n: *mut ncdirect,
    ul: u64,
    ur: u64,
    ll: u64,
    lr: u64,
    wchars: *const wchar_t,
    ylen: c_uint,
    xlen: c_uint,
    ctlword: c_uint,
) -> c_int

Draw a box with its upper-left corner at the current cursor position, having dimensions |ylen|x|xlen|. See ncplane_box() for more information. The minimum box size is 2x2, and it cannot be drawn off-screen. |wchars| is an array of 6 wide characters: UL, UR, LL, LR, HL, VL.