

User interface toolkits and higher-level tools built on top of them play an ever increasing part in developing graphical user interfaces. This paper describes the XIT system, a user interface development tool for the X Window System, based on Common Lisp, comprising user interface toolkits as well as high-level interactive tools organized into a layered architecture. We especially focus on the object-oriented design of the lower-level toolkits and show how advanced features for describing automatic screen layout, visual feedback, application links, complex interaction, and dialog control, usually not included in traditional user interface toolkits, are integrated.