pub type nk_text_width_f = Option<unsafe extern "C" fn(arg1: nk_handle, h: f32, arg2: *const c_char, len: c_int) -> f32>;
pub enum nk_text_width_f { None, Some(unsafe extern "C" fn(nk_handle, f32, *const i8, i32) -> f32), }
No value.
Some value of type T.
T