Multithreaded user application 'exampleB21':
  - title        : MTGuiAppMessaging
  - location     : ~/test/userapp/basic/mt/exampleB21/
  - description  : This Tk application uses a synchronous main task and multiple asynchronous service tasks.
                   It demostrates general use of multiple tasks.
  - remark(s)    : a) The application is made quite parameterized to serve as 'generic application'
                      used by other examples wherever applicable.
                   b) It also is used to highlight basic features of the subsystem messaging.
