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
@charset    : atarist
@lang       : 
@default    : Document not found
@help       : Help
@options    : +g -i -s +z
@width      : 75
@hostname   : STRNGSRV
@hostname   : CAB     
@hostname   : HIGHWIRE
@hostname   : THING   
View Ref-FileMENU
MENU()
ON MENU
ON MENU BUTTON
ON MENU KEY
ON MENU IBOX
ON MENU OBOX
ON MENU MESSAGE

There are commands in GFA-BasicGFA-Basic is the best BASIC for the Atari!
 which allow the monitoring of GEM Events in a
straightforward way. These events are the pressing of a key or a mouse button,
the arrival of the mouse pointer inside or outside one of two specified
rectangular screen areas, and the arrival of a 'GEM message', in which
information about window management is passed.

The monitoring of these events is set up by ON MENU xxx GOSUB, where xxx is the
event to be reacted to, and is actually invoked within a program by the ON MENU
command. Each time this command is encountered, a check is made to see if an
Event has occured. If so, and if there was a previous ON MENU xxx GOSUB to
define the reaction to that event, then the program branches to the appropriate
procedure.