openQA is an automated testing framework designed to test the entire operating system, including the installation process and graphical user interfaces. It is particularly useful for testing complex scenarios that require interaction with the system's GUI.
yuik is an abstract widget library for creating GUIs. The actual frontend can be chosen at runtime which allows the program to run under Tk, as a shell program, and even as a web-application. More frontends like an irc-bot, wxWidgets, or XUL are planned.