/**
@page GRAS_tut_tour_callbacks Lesson 4: Attaching callbacks to messages
+\section GRAS_tut_tour_callbacks_toc Table of Contents
+ - \ref GRAS_tut_tour_callbacks_declare
+ - \ref GRAS_tut_tour_callbacks_attach
+ - \ref GRAS_tut_tour_callbacks_handle
+ - \ref GRAS_tut_tour_callback_recap
+
+<hr>
+
Our program is well and good, but if we had to write a longer program,
explicitely waiting for messages of a given type would not be really
practical. To add some more dynamism, what we want to do is to attach
the next one, and so on. I'm not sure there is any sensible use of this
feature, but it's possible ;)
-\ref GRAS_tut_tour_globals
+Go to \ref GRAS_tut_tour_globals
*/