Executes all drawing function calls to a given port within the body of the macro with foreground and background colors swapped.
A graphic port.
A body of Lisp code.
The return value of the last form executed in
macro ensures that all drawing function calls to
within the body of the macro are executed with the
slots of the graphics state of the port swapped around.
LispWorks CAPI Reference Manual - 21 Dec 2009