Add header files so that make distcheck is happy. (INCLUDES): Add -D_GNU_SOURCE for asprintf. Someone motivated may want to find a more portable approach. (EXTRA_DIST): Add reference images for the sake of make distcheck.
Don't AC_SUBST a dozen different FOO_CFLAGS and FOO_LIBS. Instead, incrementally build up just CAIRO_CFLAGS and CAIRO_LIBS.
Don't list flags that should get picked up via dependency information through Requires.
Add description of move_to_show_surface.