X Athena Widgets
X Athena Widgets or Xaw is a GUI widget library for the X Window System. Developed as part of Project Athena, Xaw was written under the auspices of the MIT X Consortium as a sample widget set built on X Toolkit Intrinsics (Xt); Xt and Xaw are collectively known as the X Toolkit. Xaw has been largely superseded by more sophisticated toolkits like Motif, GTK+, and Qt but it is still maintained (by the X.Org Foundation) and is available as part of most X Window System installations. The library, like other core parts of X, is licensed under the MIT License.
In a talk for USENIX, X pioneer Jim Gettys remarked that although Athena widgets were "ugly", they were often used in the period of X history that he describes as the "GUI wars", as a safe alternative to the competing Motif and Open Look toolkits.