There are a few things you probably noticed in the previous examples
that need explaining. The gint, gchar, etc. that you see are typedefs
to int and char, respectively, that are part of the GLlib system. This
is done to get around that nasty dependency on the size of simple data
types when doing calculations.
A good example is "gint32" which will be typedef'd to a 32 bit integer
for any given platform, whether it be the 64 bit alpha, or the 32 bit
i386. The typedefs are very straightforward and intuitive. They are
all defined in glib/glib.h (which gets included from gtk.h).
You'll also notice GTK's ability to use GtkWidget when the function
calls for an Object. GTK is an object oriented design, and a widget
is an object.
