How do windows set their icons?

[Christopher DeMarco]

Hi all...  I found a thread from  Jan that addresses  my question, but
the implied  answer is  never  made explicit.  The subject  is "window
icon", from Jan 20 2004.

I'm running Openbox  3.1, hand-compiled, on   an up-to-date Red Hat  9
system.   I'm running   it "naked", with   only a  gnome-panel   and a
gnome-settings-daemon running to possibly complicate things.

I have a bunch of apps (XEmacs, JPilot) which supply nice little icons
in the window titlebar, but many others (FireFox, aterm) which do not.

In the thread referenced above, Marc Wilson said 

  "The  icon   used for  windows  **that   don't  provide one**  is  a
  compile-time option." [emphasis mine]

How exactly do windows (apps?) "provide icons"?  

Thanks!

-- 
~ You are in a maze of twisty passages, all alike.

  Christopher DeMarco
  Product Research and Development
  My Directory Sdn Bhd (www.md.com.my)
  cdemarco at md.com.my
  +6013 389 5658