XView
XView is a widget toolkit from Sun Microsystems introduced in 1988. It provides an OPEN LOOK user interface for X Window System applications, with an object-oriented application programming interface for the C programming language. Its interface, controls, and layouts are very close to that of the earlier SunView window system, making it easy to convert existing applications from SunView to X. Sun also produced the User Interface Toolkit, a C++ API to XView.
The XView source code has been freely available since the early 1990s, making it the "first open-source professional-quality X Window System toolkit". XView was later abandoned by Sun in favor of Motif, and more recently GTK+.
XView was reputedly the first system to use right-button context menus, which are now ubiquitous among computer user interfaces.
