
Example "presentation style" framework and "visibox" demo

File  presentation.lisp  contains the framework; see the comments at
the beginning of the file.  Compiler warnings about "undefined functions"
(contains-xy-p, overlaps-region-p, redraw, enter, exit) can be ignored;
these methods make up a protocol that must be supplied by an application.

The sample application is in file  vb-demo.lisp ; see the comments with
the function vb-demo for some basic things to try.

