Introduction

Normally, this is the level at which most X applications are developed. There are two parts to the X Toolkit, the X Toolkit intrinsics, known as Xt, and an Xt compatible widget set. The X Toolkit intrinsics is a set of routines for creating and managing widgets. A widget set provides the application programmer with user interface components such as buttons, scroll bars, menus, etc., which conform to a particular user interface style and have a characteristic `look and feel'.

Two Xt compatible widget sets are Athena, from MIT, and Motif, from OSF. The Athena widget set was developed by the originators of X as an experimental widget set for testing purposes. Although it is widely used, it has a somewhat crude, slightly inconsistent user interface style, than its OSF counterpart, Motif. The Motif widget set is a commercial product, with greater functionality and a more fashionable user interface style which is controlled by strict guidelines.