Free Widget Foundation (FWF) [TheOldNet][Direct] -
An international, volunteer effort to collect freely-redistributable graphical user-interface modules (widgets) for the X Window System
Marx [TheOldNet][Direct] -
Interpreted script language based on a C-like syntax that provides a quick way of creating graphical user interfaces in X Windows.
WINTERP 2.0 [TheOldNet][Direct] -
An interactive object-oriented user interface language for rapid prototyping, development and delivery of extensible applications with Motif GUIs and Xtango graphics/animation.