THE DESPATCHER HOOK

     The main purpose of displaying a menu is to allow the user to select a
     topic and then see some action! The Toolkit calls a programmer
     assigned despatcher every time the user selects a topic (that doesn't
     just call another menu).

     The despatch procedure is like a user hook. It MUST be defined,
     otherwise the menu will have no way of linking into your procedures.

     To use a procedure as a despatcher it must:

     1) Be a procedure declared with two parameters - a variable integer
     that identifies which topic was selected (i.e. the topic selection
     code) and a variable byte that is used to inform the menu system which
     refresh tasks should be performed when the despatch procedure has
     completed. For example

     PROCEDURE TASK_CALLER(VAR TOPICCODE:INTEGER; VAR RETCODE: BYTE);
     BEGIN
         ......
     END;

     2) Be declared as a far procedure, i.e. precede the procedure with a
     {$F+} compiler directive and succeed the procedure with the {$F-}
     compiler directive.

     The technique of assigning the despatcher for Turbo Pascal 5.0 is
     different from version 4.0:

     Turbo 5 Users - call the procedure Assign_Despatcher and pass the name
     of the procedure, e.g.

          ASSIGN_DESPATCHER(TASK_CALLER)

     Turbo 4 Users - a global variable Nest_Despatcher (of type Pointer)
     should point to the procedure with the @ directive, e.g.

          NEST_DESPATCHER := @TASK_CALLER