How to set background for a gtk window form using .gtkrc file

["邓超" <knifewolf gmail com>]

Hi all,
  I want to use .gtkrc file to set the background for a window form to
transparent, how to do it? I have read the tutorial at live.gnome.com, but
it looks that it just can set color for a window form. Thanks!

-- 
Deng Chao