The letter G is ubiquitous in the world of open -source software; it stands for GNU (Richard Stallman's "GNU's Not Unix"). You'll see it throughout this book in names like GTK+, GLib, GObject, and GNOME, as well as in many other software packages such as Ghostscript and gcc.
To understand the later chapters in this book, you need to learn about a fundamental library called GLib ( libglib-2.0 ). It provides basic data structures and utility functions for the GTK+ widget set and GNOME applications in general. This chapter deals with GLib's architecture and introduces the API. You'll see GLib's object system (GObject) in Chapter 2.
You can't really avoid GLib when using GNOME and GTK+. Other libraries such as ORBit use GLib, and many don't depend on any other libraries. The abstractions and utilities that GLib provides are handy for nearly any programming task and simplify ports to other platforms.
This chapter contains no graphical code. It is a concise , point-by-point guide to the most important GLib functions and data structures. You may find this material a bit dry, so you can go directly to Chapter 3 to get started with GTK+. However, you may find yourself regularly looking back to these first two chapters for reference.