Fontify symbols representing faces with that face.
Enable fontify-face-mode in the buffer where you want the previews
to be active.
Note: the symbols are tested with facep predicate which means if
the package that defines the faces is not loaded they will not be
fontified. If you want to see the previews you will have to require
the package that defines the faces first.
Read the blog for a more in depth background.
During theme or package development it is useful to see how the faces look directly during development. This saves time and provides thighter feedback loop. Happy theming!
