Via: uk.ac.southampton; Thu, 9 Sep 1993 16:23:41 +0100
From: Chris Boucher <C DOT C DOT Boucher AT southampton DOT ac DOT uk>
Date: Thu, 9 Sep 93 16:00:20 BST
To: djgpp AT sun DOT soe DOT clarkson DOT edu (djgpp)
Subject: Re: backspace <--> delete

rda AT uk DOT ac DOT cam DOT eng writes:
>   Chris Boucher <C DOT C DOT Boucher AT southampton DOT ac DOT uk> writes:
> >The trick is to look at the keyboard modifiers (INT 16 AH=02) every time
> >you read in a key - if you get a ^H and the control key isn't down then
> >it was backspace.
> 
> This works OK most of the time, but it tends to fail in some applications if
> the user types ahead - unless you can guarantee that the application is
> going to read keys immediately you may be OK, but if not, you can end up
> reading the modifiers long _after_ the key was pressed.
> 
> Example:
>     In Demacs & OEmacs (DOS/WINDOWS/DJGPP versions of GNU Emacs)
[deleted]
> This sort of behaviour is bad IMHO - editors ought to be able to cope with a
> few characters type-ahead.

Yes, I'm aware of this problem (yet another DOS limitation).  As a
matter of fact I've just finished rewriting the keyboard handling code
for OEmacs (it can now recognise *many* more keys), but this problem
still exists because, as you point out... 

> What is really needed is an INT-09 handler in GO32 which reads the modifiers
> _when the key is pressed_ and buffers keypress events as (say) keycode +
> modifier (+ timestamp ?) for the application (ditto for mouse events).

Agreed, but I think this will have to wait for GO32 1.11.

One thing to note is that any event handler should ideally come *after*
KEYB has done the necessary translations, if not it'll need different
scan code tables for each country (although these are available via the
Xfree86 Xmodmaps). 

> I think the current event library could be modified to do this, but I can't
> find any docs for it.

Hmmm, I'll take a look.

Chris.

-- 
Dr Chris Boucher                            Tel: (+44 703) 592300
Signal Processing and Control Group         Fax: (+44 703) 593033
Institute of Sound and Vibration Research   Email: ccb AT soton DOT ac DOT uk          
University of Southampton, Southampton S09 5NH, England