Topic       : The GFA-Basic Compendium
Author      : GFA Systemtechnik GmbH
Version     : GFABasic.HYP v2.98 (12/31/2023)
Subject     : Documentation/Programming
Nodes       : 899
Index Size  : 28056
HCP-Version : 3
Compiled on : Atari
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@hostname   : CAB     
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View Ref-FileON MENU MESSAGE GOSUB proc

proc: procedure name

If a message arrives in the message buffer, then the program branches to the
procedure with the name proc. The monitoring of the message buffer takes place
with each ON MENU command. The structure of the message buffer is discussed in
the section concerning MENU().

Example:

    DIM m$(10)
    FOR i%=0 TO 10
      READ m$(i%)
    NEXT i%
    DATA Desk,Redraw,-------------------------
    DATA 1,2,3,4,5,6,"",""
    OPENW 4,0,0
    MENU m$()
    ON MENU MESSAGE GOSUB read_message
    PRINT AT(1,1);
    REPEAT
      ON MENU
    UNTIL MOUSEK=2
    '
    PROCEDURE read_message
      IF MENU(1)=20
        PRINT CHR$(7);
        PRINT "A screen section must be redrawn"
      ELSE
        PRINT CHR$(7);
        PRINT "Something has happened !!!"
      ENDIF
    RETURN

--> To test this program, an accessory must be loaded. If selected, then the
    program announces that a screen section was covered and has to be redrawn
    (see also MENU()). At the beginning this message appears once.  The program
    can be terminated with a press of the right mouse button.

Memo: If the procedure used with ON MENU MESSAGE is undefined the compiler
      will not issue and error message. Instead the compiler writes a bad
      binary where ON MENU MESSAGE is translated into JSR 0.l!

evnt_mesag()+