type of data
You may find that there are several places in the previous examples to explain. GINT, GCHAR, etc. To see the definition of int and char, they are part of the GLIB system. This is used to avoid low-level dependence on simple data types during calculation.
A good example is that "GINT32" is defined as 32-bit integers of any platform, whether 64-bit Alpha or 32-bit I386. This type is defined very intuitive.
The GTK design is an object-oriented, one component is an object.
