On Fri, Mar 06 2015, Stefan Monnier wrote:

Hi Stefan,

>> +    ;; Call font-lock-mode to refresh the buffer when used e.g. interactively
>> +    (font-lock-mode 1)))
>
> I'm not sure I understand why you need that.  Do you really mean that
> rainbow requires font-lock-mode to be enabled?

To work rainbow-mode needs font-lock-mode, that's for sure.
Without that change, even if font-lock-mode is activated, typing "M-x
rainbow-mode" does not refresh the buffer correctly when it's enabled or
disabled. Adding this line fixes that.

So that's the only way we found to refresh the current fontification of
a buffer with font-lock-mode. If there's a better way, let me know!

Cheers,
-- 
Julien Danjou
;; Free Software hacker
;; http://julien.danjou.info