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Date: Sun, 11 Apr 2010 11:33:05 +0200
From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: 1.7.3: Backspace key not working in GNU screen.
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On Apr 10 22:09, Andy Koppe wrote:
> Christopher Faylor wrote:
> > I'm not 100% sure that this is the right fix but the new snapshot at
> > least works around the problem.
> 
> Thanks.
> 
> > The problem is that screen explicitly sets VERASE to 0.  I believe that
> > it does that to mean "there is really no erase character since I'm
> > handling that".
> 
> You're right. Zero is the value of the _POSIX_VDISABLE constant for
> disabling special characters. Therefore, using c_cc[VERASE] as the
> backspace keycode was a bad idea all along. Sorry for suggesting it in
> the first place.
> 
> > That should not cause Cygwin to send a null character.
> > I think it should probably just send the default \177 character.
> 
> Makes sense given the botched design, but of course it does mean that
> the user's backspace keycode setting is ignored. Also, 'screen' would
> be expecting what was set in c_cc[VERASE] as the backspace keycode.

That would be surprising.  If you set VEARSE to 0 on Linux, a following
tcgetattr returns 0 as the VERASE value.  stty prints "<undef>".  The
same holds true for other settings like VKILL, VINTR, etc.  So, if the
process sets VERASE to 0, and is then puzzled to get a 0 VERASE value
from the OS, it's the application's fault.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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