xbox1	simple box
xbox2	simple form
xbox3	invokes dialog, with text entry, not using XtCallbackExclusive
xbox4	simple box using static argument lists and callback lists
xbox5	invokes dialog, without text entry, using XtCallbackExclusive (callback list with PrepareDialog)
xbox6	Uses R3Initialize utility function and explicit application contexts

Ex3-6	Example 3-6 from book:  passing a number to a callback through client_data
Ex3-7	Example 3-7 from book:  passing a structure to a callback through client_data

R3Initialize.c	This function is intended to be used under R3 as
a replacement for XtInitialize.  It has the same arguments, except that
the application name argument in XtInitialize that was unused is
replaced by an application context return argument.  This application
context can be passed around to functions like XtAppMainLoop.
