Squeak is an OpenSource and super-portable implementation of a multi-media capable Smalltalk-80 based object-oriented programming environment. It is written entirely in Smalltalk and has a high-performance VM, created by compiling the Smalltalk VM code into efficient and portable C code. It now uses the Self language's Morphic User Interface but still provides the original MVC GUI as well.
ViewKlass is a C++ framework for developing applications that use the LessTif or OSF/Motif(tm) user interface toolkits. In particular it provides classes that support the creation of reusable components. It also provides classes that encapsulate some of the more difficult and tedious aspects of Motif development. These include classes to handle the creation of windows, dialogs, and menus. ViewKlass is an open source implementation of SGI's ViewKit(tm), and should eventually become source code compatible with a large subset of of that API.
CLIP is a Clipper/XBase compatible compiler with initial support other xBase dialects. It features support for international languages and character sets. It also features OOP, a multiplatform GUI based on GTK/GTKextra, all SIX/Comix features (including hypertext indexing), SQL and ODBC drivers, a C-API for third-party developers, a few wrappers for popular libraries (such as BZIP, GZIP, GD, Crypto, and Fcgi), a multitasking client and application server based on TCP/IP sockets, object data base utilities, and a functions library.
NovaTK is an object-oriented, cross-platform GUI toolkit. One of the focuses of NovaTK is to facilitate rapid development of cross-platform applications requiring fewer lines of code. The event system is based upon a powerful callback mechanism that makes application design simpler, easier to read, and logical.
The Oculus Layout System supplies a Java layout API, and an easy-to-use visual builder, which works with both Swing and AWT. Main features include a proprietary stretching model, which enables the system to automatically infer how to properly stretch almost any user interface, and a cursor-based layout paradigm which dramatically improves the readability and maintainability of the layout code.
Steph is a portable C library for text mode windows, menus, dialogs, etc. The interface with the underlying system is provided by a separate library, so to port to a new system, only the interface library needs to be rewritten. Interface libraries are provided for Unix/Curses and IBM PC compatibles running DOS.