Some confusing about this toolkits?
Introduction
GTK+ is a multi-platform toolkit for creating graphical user interfaces. Offering a complete set of widgets, GTK+ is suitable for projects ranging from small one-off projects to complete application suites.
GTK+ is free software and part of the GNU Project. However, the licensing terms for GTK+, the GNU LGPL, allow it to be used by all developers, including those developing proprietary software, without any license fees or royalties.
GTK+ is based on three libraries developed by the GTK+ team:
GLib is the low-level core library that forms the basis of GTK+ and GNOME. It provides data structure handling for C, portability wrappers, and interfaces for such runtime functionality as an event loop, threads, dynamic loading, and an object system.
Pango is a library for layout and rendering of text, with an emphasis on internationalization. It forms the core of text and font handling for GTK+-2.0.
The ATK library provides a set of interfaces for accessibility. By supporting the ATK interfaces, an application or toolkit can be used with such tools as screen readers, magnifiers, and alternative input devices.
GTK+ has been designed from the ground up to support a range of languages, not only C/C++. Using GTK+ from languages such as Perl and Python (especially in combination with the Glade GUI builder) provides an effective method of rapid application development.
What is the + in GTK+? [GTK 2.x]
Peter Mattis informed the gtk mailing list that:
"I originally wrote gtk which included the three libraries, libglib, libgdk and libgtk. It featured a flat widget hierarchy. That is, you couldn't derive a new widget from an existing one. And it contained a more standard callback mechanism instead of the signal mechanism now present in gtk+. The + was added to distinguish between the original version of gtk and the new version. You can think of it as being an enhancement to the original gtk that adds object oriented features."
Although much has changed with GTK+, and Peter, Spencer and Josh don't have any direct involvement these days, the name is kept to keep a link with the heritage of GTK+.
GTK+ is now additionally based upon the Pango and ATK libraries, that provide text layout and rendering and accessibility interfaces.
Does the G in GTK+, GDK and GLib stand for? [GTK 2.x]
GTK+ == The GIMP Toolkit
GDK == GTK+ Drawing Kit
GLib == G Library
References:
http://www.gtk.org/
