highlight lines with trailing spaces, lines longer than 80 chars and tabs

.emacs

;; taken from http://www.emacswiki.org/emacs/EightyColumnRule by http://www.emacswiki.org/emacs/TimOCallaghan

(custom-set-faces
   '(my-tab-face            ((((class color)) (:background "grey10"))) t)
   '(my-trailing-space-face ((((class color)) (:background "gray10"))) t)
   '(my-long-line-face ((((class color)) (:background "gray10"))) t))
  (add-hook 'font-lock-mode-hook
            (function
             (lambda ()
               (setq font-lock-keywords
                     (append font-lock-keywords
                             '(("\t+" (0 'my-tab-face t))
                               ("^.\\{81,\\}$" (0 'my-long-line-face t))
                               ("[ \t]+$"      (0 'my-trailing-space-face t))))))))