You say mkid in the root directory of the source tree and later can
use gid or Emacs M-x gid to find where keywords appear. The output is
just like from grep and thus emacs can take you to the source with C-c
C-c on the interesting line.
This is very good on finding references to some function or structure
member.
----- Marko Kohtala - Marko.Kohtala@ntc.nokia.com, Marko.Kohtala@hut.fi