Eli Zaretskii <eliz@gnu.org> writes:

> One more nit, about these fragments: [...] it is better to check the
> frame type at run time, [...]

>  #ifdef HAVE_X_WINDOWS
>    if (FRAME_X_P (f))
>      *add_y += FRAME_X_OUTPUT (f)->y_pixels_outer_diff;
>    else
>  #elif defined (HAVE_NTGUI)
>    if (FRAME_W32_P (f))
>      *add_y += f->y_pixels_diff;
>  #endif
>
> etc., you get the idea.

I don't think that quite does what you have in mind, but I get it.