.emacs

(defmacro smart-tabs-advice (function offset)
  (defvaralias offset 'tab-width)
  `(defadvice ,function (around smart-tabs activate)
     (cond
      (indent-tabs-mode
       (save-excursion
         (beginning-of-line)
         (while (looking-at "\t*\\( +\\)\t+")
           (replace-match "" nil nil nil 1)))
       (setq tab-width tab-width)
       (let ((tab-width fill-column)
             (,offset fill-column))
         ad-do-it))
      (t
       ad-do-it))))