[cairo] cairo_ft_font_face_create_for_ft_face Subtlety

[Lawrence D'Oliveiro]

I wrote:

> I discovered this in the process of messing about with Multiple
> Master/TrueType GX fonts. It looks like Cairo’s caching interferes
> somewhat with the behaviour of these: to get around this, you have to
> load the same font multiple times so that you can set different values
> for the design coordinates on each copy.

Alternatively, it would be nice if there were a call

    void cairo_font_face_flush
      (
        cairo_font_face_t * font_face
      );

which invalidated all caches associated with that font face. That might
be the simplest solution.