'gyachi-1.1.0' is the newest version, and not a word about libgtkhtml,
when running configure (libgtkhtml2 is required, according to the config files)
(grep gtkhtml gyachi-1.1.0/*)
Version 1.1.0 compiles with no problems on a clean Slacware 12,
so I can't see why you have the errors.
Suggest : reinstall libgtkhtml-2.11.0-i486-1.
No need to uninstall gtk-1.2, total different names for all files and
Some dependencies are not checked by 'configure'. You will also need :
...(lib)jasper => version 1.900.1 source from
...libmcrypt (=> libmcrypt-2.5.8-i486-1sl.tgz)
...xmms (xmmsctrl.h is required)