changing tabbar font color...

[Brendan Miller <catphive@catphive.net>]

I have tabbar, but the gray on gray colors are a little hard to see,
so I wanted to customise the font color... I got some example code
from google to start out from, but it generates this error:

error: Invalid face, tabbar-default-face

The relevant section of my .emacs looks like this:

;; tabbar
(require 'tabbar)
(tabbar-mode)
(global-set-key [(s-right)] 'tabbar-forward)
(global-set-key [(s-left)] 'tabbar-backward)

;; example tabbar coloring code...
  (set-face-attribute
   'tabbar-default-face nil
   :background "gray60")
  (set-face-attribute
   'tabbar-unselected-face nil
   :background "gray85"
   :foreground "gray30"
   :box nil)
  (set-face-attribute
   'tabbar-selected-face nil
   :background "#f2f2f6"
   :foreground "black"
   :box nil)
  (set-face-attribute
   'tabbar-button-face nil
   :box '(:line-width 1 :color "gray72" :style released-button))
  (set-face-attribute
   'tabbar-separator-face nil
   :height 0.7)