ArgoUML is a pure Java open source UML CASE tool that provides cognitive support for object-oriented design. ArgoUML provides some of the same editing and code generation features of a commercial CASE tool, but it focuses on features that enhance usability and support the cognitive needs of designers. Uses XML file formats: XMI and PGML.
nvi is a version of the vi editor which supports all the historic ex/vi features except for open mode and the lisp edit option (e.g., it has a fully implemented underlying ex mode). It contains a number of additional features, including an experimental GTK frontend in the development version.
ClassyTk is an extension of Tk based on the ClassyTcl Object system. It adds a lot of improvements to Tk, ranging from drag and drop support (between Tk apps) and a configuration system to a large set of new widgets and commands, written using the object system. It also contains a GUI Builder that can be used to graphically create interfaces. It is invoked via the cbuild command in the bin directory. There are also some sample (but useable) applications created with ClassyTk: a very useable editor, a calculator, a drawing program, and more.
Traditional vi is derived from the 4BSD source and includes support for modern operating systems, 8-bit input, multi-byte character encodings like UTF-8, and features demanded by POSIX.2. It contains few additions beyond this, so it is of interest for those who look for a small but well-defined vi implementation close to that of most commercial Unix systems. It also has some features to cope with primitive terminals or slow connections.