Changing the function of a key
- Last Updated: January 17, 2024
- 2 minute read
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Changing the function of a key
You can globally change ABL key functions by modifying your environment. For more information on modifying your environment, see the topics on colors and fonts in this book and the topics on user interface environments in Manage ABL Applications.
Although ABL has defined functions for several of the keys on your keyboard, you can redefine those keys to perform other functions within an application. In addition, you can assign functions to any of the other keyboard keys.
Suppose the user is accustomed to pressing F2 to get help information and F1 to signal that they are finished
entering data. Although the AVM usually treats F2 as GO and F1 as HELP, you
can switch the functions of those keys as demonstrated in the i-action.p procedure.
i-action.p
|
In this procedure, the ON statements redefine
the function of F1, F2, and CTRL+X.
Run this procedure, then press F1.
You can see that F1 now performs
the GO function, normally performed by F2. If you press CTRL+X, the AVM rings the terminal
bell. The new key definitions are in effect for the duration of
the session, unless you redefine them. Also, on UNIX, any key label
you use in an ON statement must have an entry in
the PROTERMCAP file for your terminal.
When you use the ON statement, you use the name
of the key whose function you are redefining, followed by the action
you want to take when the user presses that key, as shown in the
following figure.

The i-action.p procedure uses three actions: GO, HELP,
and BELL. There are many other actions you can
use when redefining the function of a key. The following table lists
these actions.
| Action | Default key |
|---|---|
BACKSPACE |
BACKSPACE |
BACK–TAB |
SHIFT+TAB, CTRL+U, CODE+TAB |
BELL |
– |
CLEAR |
F8, CTRL+Z, CODE+Z |
CURSOR–UP |
×, CTRL+K |
CURSOR–DOWN |
±, CTRL+J |
CURSOR–LEFT |
?, CTRL+H |
CURSOR–RIGHT |
?, CTRL+L |
DELETE–CHARACTER |
DEL |
ENDKEY |
– |
END–ERROR |
F4, CTRL+E, CODE+E, ESC (Windows) |
ERROR |
– |
GO |
F2, CTRL+X, CODE+X |
HELP |
F1, HELP, CTRL+W, CODE+W |
HOME |
HOME, ESC H (UNIX) |
INSERT–MODE |
F3, INSERT, CTRL+T, OVERTYPE |
RECALL |
F7, CTRL+R, CODE+R |
RETURN |
RETURN |
STOP |
CTRL+BREAK (Windows), CTRL+C (UNIX) |
TAB |
TAB, CTRL+I |