Avoid font-lock reset in `gnus-message-citation-mode'

* lisp/gnus/gnus-cite.el (gnus-message-citation-mode): Use
`font-lock-add-keywords' and `font-lock-remove-keywords' instead of
modifying font-lock defaults.  Make no font-lock changes until
`font-lock-mode' is active.

Thanks to Morgan Willcock

diff --git a/lisp/gnus/gnus-cite.el b/lisp/gnus/gnus-cite.el
index 04abdfc0d1b404ad64d15e9ac55c5b2ec824e1f6..3fde9baa0fe23e3cb58f9dfd6d66ec702dbf8935 100644 (file)
--- a/lisp/gnus/gnus-cite.el
+++ b/lisp/gnus/gnus-cite.el
@@ -1122,31 +1122,17 @@ Returns nil if there is no such line before LIMIT, t otherwise."
 When enabled, it automatically turns on `font-lock-mode'."
   :lighter ""
   (when (derived-mode-p 'message-mode)
-    ;; FIXME: Use font-lock-add-keywords!
-    (let ((defaults (car font-lock-defaults))
-         default) ;; keywords
-      (while defaults
-       (setq default (if (consp defaults)
-                         (pop defaults)
-                       (prog1
-                           defaults
-                         (setq defaults nil))))
-       (if gnus-message-citation-mode
-           ;; `gnus-message-citation-keywords' should be the last
-           ;; elements of the keywords because the others are unlikely
-           ;; to have the OVERRIDE flags -- XEmacs applies a keyword
-           ;; having no OVERRIDE flag to matched text even if it has
-           ;; already other faces, while Emacs doesn't.
-           (set (make-local-variable default)
-                (append (default-value default)
-                        gnus-message-citation-keywords))
-         (kill-local-variable default))))
-    ;; Force `font-lock-set-defaults' to update `font-lock-keywords'.
-    (setq font-lock-set-defaults nil)
-    (font-lock-set-defaults)
-    (if font-lock-mode
-       (font-lock-flush)
-      (gnus-message-citation-mode (font-lock-mode 1)))))
+    (if (not font-lock-mode)
+        (gnus-message-citation-mode (font-lock-mode 1))
+      (if gnus-message-citation-mode
+         ;; `gnus-message-citation-keywords' should be the last
+         ;; elements of the keywords because the others are unlikely
+         ;; to have the OVERRIDE flags -- XEmacs applies a keyword
+         ;; having no OVERRIDE flag to matched text even if it has
+         ;; already other faces, while Emacs doesn't.
+         (font-lock-add-keywords nil gnus-message-citation-keywords t)
+        (font-lock-remove-keywords nil gnus-message-citation-keywords))
+      (font-lock-flush))))
 
 (defun turn-on-gnus-message-citation-mode ()
   "Turn on `gnus-message-citation-mode'."