On 2016-12-06 Tue 01:27 GMT-0800, Hong Xu <hong@topbug.net> wrote:

> 	* gnus-cite.el (gnus-message-citation-mode): Fontify if the major
> 	mode is derived from message-mode (not necessarily equal to
> 	message-mode).
> ---
>  lisp/gnus/gnus-cite.el | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lisp/gnus/gnus-cite.el b/lisp/gnus/gnus-cite.el
> index 502a3be35550..e012b256d09d 100644
> --- a/lisp/gnus/gnus-cite.el
> +++ b/lisp/gnus/gnus-cite.el
> @@ -1204,7 +1204,7 @@ gnus-message-citation-mode
>    nil ;; init-value
>    "" ;; lighter
>    nil ;; keymap
> -  (when (eq major-mode 'message-mode)   ;FIXME: Use derived-mode-p.
> +  (when (derived-mode-p 'message-mode)
>      ;; FIXME: Use font-lock-add-keywords!
>      (let ((defaults (car (if (featurep 'xemacs)
>  			     (get 'message-mode 'font-lock-defaults)


Still consider this patch? The fix is quite straightforward.