e93 is a portable window-based text editor oriented to the needs of programmers. It uses the mouse, selections, cut/copy/paste, and closely follows the model of editors on the Macintosh and NeXT platforms. It supports columnar selection by allowing multiple pieces of the text to be selected simultaneously (this is perhaps its most unique feature), imposes no limits on the line length, file length, or number of simultaneous files which it can edit, and has many other features.
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.
PEP is a modeling and verification framework for parallel systems. It provides a large number of different modelling languages (e.g. SDL, B(PN)^2, Petri nets, Process algebras and Finite Automata), and verification techniques (e.g. reachability and temporal logic model checking). Due to its Tcl/Tk-based GUI, PEP is easily extensible to other analysis or specification tools. The framework offers fully integrated simulation and debugging features on all levels.