The hush library contains the classes kit, event, handler, widget and item. In addition to these, hush provides the class session. Application programmers are minimally required to derive a class, say application, from session and redefine the function main. When the program is to be used as a script interpreter, the function prelude may be redefined to allow for initializing external packages or other components of the DejaVu framework.
As a comment, the hush library originated as a collection of classes giving the C++ programmer convenient access to the Tcl/Tk window programming toolkit. Its design has been inspired by the Interviews library. However, although less powerful wit respect to device-independent graphics, its class structure is less complex and, as experience shows, much easier to employ by undergraduate students. In addition, it offers a rich collection of user interface widgets.