(eval-after-load 'erc-track
  '(progn
     (defun erc-bar-update-overlay ()
       "Update the overlay for current buffer, based on the content of
erc-modified-channels-alist. Should be executed on window change, "
       (interactive)
        (let* ((info (assq (current-buffer) erc-modified-channels-alist))
	       (count (cadr info)))
	     (if (and info (> count erc-bar-threshold))
		        (move-overlay erc-bar-overlay
				           (line-beginning-position (- count))
					        (line-end-position (- count))
						     (current-buffer))
	            (delete-overlay erc-bar-overlay))))

     (defvar erc-bar-threshold 1
       "Display bar when there are more than erc-bar-threshold unread messages")
     (defvar erc-bar-overlay nil
       "Overlay used to set bar")
     (setq erc-bar-overlay (make-overlay 0 0))
     (overlay-put erc-bar-overlay 'face '(:underline "black"))
     ;;put the hook before erc-modified-channels-update
     (defadvice erc-track-mode (after erc-bar-setup-hook
				            (&rest args) activate)
       ;;remove and add, so we know it's in the first place
       (remove-hook 'window-configuration-change-hook 'erc-bar-update-overlay)
       (add-hook 'window-configuration-change-hook 'erc-bar-update-overlay))
     (add-hook 'erc-send-completed-hook (lambda (str)
					    (erc-bar-update-overlay)))
))