ClassyTcl is a dynamically loadable object system for Tcl. Both a Tcl-only and a C implementation are available. It also doesn't require patches to the Tcl core, which makes installation and maintenence easier. Performance is quite adequate. The C version is gives extra speed, and makes it possible to implement some methods in C. In contrast to other object systems for Tcl, it is not modeled after the object system designed for a completely different language, such as C. The system is simple but flexible. Classes and objects are dynamic, and can easily be queried, changed, and debugged at runtime.
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.