;; Highlight "FIXME" comments 
(defface fixme-face 
  '((t (:weight bold :box (:line-width 2 :color "orange")))) 
  "The faced used to show FIXME lines.")
(defface todo-face 
  '((t (:weight bold :box (:line-width 2 :color "green")))) 
  "The faced used to show TODO lines.")
(defface xxx-face 
  '((t (:weight bold :box (:line-width 2 :color "red")))) 
  "The faced used to show XXX lines.")

(defun show-fixme-lines (&optional arg) 
  "Emphasise FIXME comments. If ARG is positive, enable highlighting. If ARG is negative, disable highlighting. Otherwise, toggle highlighting." 
  (interactive) 
  (if (or (and (not arg) (assoc "FIXME" hi-lock-interactive-patterns)) 
          (and arg (minusp arg))) 
      (progn 
        (unhighlight-regexp "FIXME") 
        (unhighlight-regexp "TODO") 
        (unhighlight-regexp "XXX")) 
    (progn 
      (highlight-phrase "FIXME" 'fixme-face)
      (highlight-phrase "TODO" 'todo-face)
      (highlight-phrase "XXX" 'xxx-face)
      )))