I have downloaded a number of tar source packages from gnome.or and other
sites for compliation on my RH6.1 system. After uncompressing the desired
program, the confiure script tries to determine the location and version of
gtk but fails to do so with the following message:

checking for gtk-config... (cached) /usr/bin/gtk-config
checking for GTK - version >= 1.0.0... no
*** Could not run GTK test program, checking why...
*** The test program failed to compile or link. See the file config.log
for the
*** exact error that occured. This usually means GTK was incorrectly
installed
*** or that you have moved GTK since it was installed. In the latter
case, you
*** may want to edit the gtk-config script: /usr/bin/gtk-config

All the config.log files would say

  printf("\n*** 'gtk-config --version' returned %d.%d.%d, but GTK+
(%d.%d.%d)\n",
             1, 2, 5,
             gtk_major_version, gtk_minor_version, gtk_micro_version);
      printf ("*** was found! If gtk-config was correct, then it is
best\n");
      printf ("*** to remove the old version of GTK+. You may also be
able to fix the error\n");
      printf("*** by modifying your LD_LIBRARY_PATH enviroment variable,
or by editing\n");
      printf("*** /etc/ld.so.conf. Make sure you have run ldconfig if
that is\n");
      printf("*** required on your system.\n");
      printf("*** If gtk-config was wrong, set the environment variable
GTK_CONFIG\n");
      printf("*** to point to the correct copy of gtk-config, and remove
the file config.cache\n");
      printf("*** before re-running configure\n");

Upon consulting the rpm database I found that the following gtk packages
were installed

gtk+-1.2.5-2
gtk+-devel-1.2.5-2
gtk+10-1.0.6-6
gtk-engines-0.7-1

I had to go to gtk.org, download, make and install gtk 1.2.5 and glib
before a confiure script would recognize that gtk was 9installed on my
system.