Trouble finding gtk...

[Jonathan R Blandford <jrb MIT EDU>]

(I apologize if this appears twice... I sent it a while ago - but it
 doesn't appear to have arrived yet)

Hi,
  I did a cvs update on gnome-libs for the first time in about a week,
and tried to recompile it.  However, configure is now unable to find
gtk, and gives the following error message:

checking for GTK - version >= 1.0.0... no
configure: error: GTK not installed

I have the latest gtk from CVS, and configure worked fine a week ago.
What has changed in the meantime?

Thanks,
-jonathan