The program must be compiled with the GtkSpell C flags and built with the
GtkSpell libs. Depending on how your program is compiled, you must include the
module gtkspell-2.0 along with gtk+-2.0
in your calls to pkg-config.
Building Using Autoconf
In configure.ac, modify the call to
PKG_CHECK_MODULES to include
gtkspell-2.0, like this: