X Toolkit Intrinsics (also known as Xt, for X toolkit) is a
library
A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...
that implements an
API to facilitate the development of programs with a
graphical user interface
A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...
(GUI) for the
X Window System. It can be used in the
C language (or any language that can use the C
API, such as
C++). Design took place late 1980s to early 1990s.

The low-level library
Xlib is the client-side implementation of the
X11 protocol. It communicates with an
X server, but does not provide any function for implementing
graphical control elements ("widgets"), such as
buttons or
menus. The Xt library provides support for creating widget types, but does not provide any itself. A programmer could use the Xt library to create and use a new type of widget. Xt implemented some object oriented concepts, such as inheritance (the user could make their own button by reusing code written for another type of button), events, and callbacks.
Since the graphical user interface of applications typically requires a number of widget types, most developers were reluctant to write their own, and instead prefer to use libraries such as
Xaw,
Motif and
OLIT that provide a set of widgets.
Xt programs had a notorious problem of being unusable if the "app-defaults Xrm database", a text file describing all the widgets, could not be found. Most modern, widely-used toolkits such as
GTK and
Qt do not use the Xt library. Rather, they use
Xlib or
XCB directly.
External links
''X Toolkit Intrinsics – C Language Interface''pdf,
X.Org Foundation
*
The place of Intrinsics in X11 Professor David Marshall, Cardiff School of Computer Science,
Cardiff University
Cardiff University () is a public research university in Cardiff, Wales. It was established in 1883 as the University College of South Wales and Monmouthshire and became a founding college of the University of Wales in 1893. It was renamed Unive ...
TestXt2 Example C program that creates a Menu Bar using just Xt/Xaw
*
*
*
X-based libraries
C (programming language) libraries
Graphics libraries
{{prog-lang-stub