X-Recipient:	archive-cygwin AT delorie DOT com
DomainKey-Signature:	a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:date:from:to:subject:message-id:reply-to
	:references:mime-version:content-type:in-reply-to; q=dns; s=
	default; b=Ux1uOrvUcN55lCjiMQUqDeiq8SA5eJsmFdhd1v/EoegCQWoXP33j8
	h+RO2p3qTHF9HoZyd5gA/giPQq2m6wG4pPu070gOiaWpJs65dyQL7zvqeZ2+QXZI
	9fR+SAa0SI7B+CW15MIkMe+hFBsUPxYflriVPzE34xascWy0jCPCKs=
DKIM-Signature:	v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:date:from:to:subject:message-id:reply-to
	:references:mime-version:content-type:in-reply-to; s=default;
	bh=CpgrYM43VERtRjCKMgwsVZ7r3y0=; b=azMGo0ve8oBYLucjEZZ7e04ANiRv
	o1Y0z34zZGB7FhUoUGIaKi32hyUer8hAdwXlUJZDId2uDwf1wvTszimvbgtEEPvv
	WeODIAOeZKPsX2B2IdbX+D3LcpQjTRq1szS6cGepjo4rAYJ4Jindu75NzIn1ByrP
	kDxynbpZAAQbCcA=
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Authentication-Results:	sourceware.org; auth=none
X-Virus-Found:	No
X-Spam-SWARE-Status:	No, score=-95.0 required=5.0 tests=AWL,BAYES_00,GOOD_FROM_CORINNA_CYGWIN,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_BRBL_LASTEXT,RCVD_IN_PBL,RCVD_IN_SORBS_DUL,RDNS_DYNAMIC autolearn=ham version=3.3.2 spammy=H*i:sk:7c08fa8, H*f:sk:7c08fa8, admit, click
X-HELO:	calimero.vinschen.de
Date:	Wed, 3 Aug 2016 14:41:27 +0200
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: [PATCH] Strange behavior of cmd.exe when hammered with clear screen operations from Cygwin program.
Message-ID:	<20160803124127.GA17526@calimero.vinschen.de>
Reply-To:	cygwin AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
References:	<0ee6699f198b7b0f588054ba2f829db5 AT mail DOT kylheku DOT com> <20160728195135 DOT GC26311 AT calimero DOT vinschen DOT de> <20160729103927 DOT GB5963 AT calimero DOT vinschen DOT de> <f00a28ea8ac7ea704e6374f8a5cc5c88 AT mail DOT kylheku DOT com> <20160801085109 DOT GC3470 AT calimero DOT vinschen DOT de> <7c08fa896bb7dadcca91f1a7a26ddf20 AT mail DOT kylheku DOT com>
MIME-Version:	1.0
In-Reply-To:	<7c08fa896bb7dadcca91f1a7a26ddf20@mail.kylheku.com>
User-Agent:	Mutt/1.6.2 (2016-07-01)

--3MwIy2ne0vdjdPXF
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Aug  2 23:19, Kaz Kylheku wrote:
> On 01.08.2016 01:51, Corinna Vinschen wrote:
> > On Jul 29 08:59, Kaz Kylheku wrote:
> > > On 29.07.2016 03:39, Corinna Vinschen wrote:
> > > > I applied a patch to perform this action.  It's in the latest
> > > > 2.6.0-0.5 test release I just announced.
> > > [...]
> > > I've done some interactive testing with this using
> > > the interpreter for a Lisp dialect. I would evaluate
> > > this expression to generate a 5 second delay and then
> > > a clear screen VT100 sequence:
> > >=20
> > >   (progn (usleep 5000000) (put-string "\e[2J"))
> > >=20
> > > during this time, I would scroll the buffer somewhere.
> > >=20
> > > I also tested with a cursor position somewhere in the
> > > middle of the window, having issued:
> > >=20
> > >   (put-string "\e[12H")
> > >=20
> > > The programming language details don't matter; we
> > > could do this with bash echo $'\e...' and sleep 5.
> > > [...]
> > > With the third patch, I've run into behavior in which the
> > > display isn't cleared at all if the clear is issued
> > > in a scrolled-back state.
> >=20
> > I can't reproduce this.  If I don't click wildly on the scroll bat at
> > the time the clear screen action takes place (so I move the window right
> > after clear screen), the cursor is positioned at the top of the screen,
> > at the end of the buffer.  So, how would I reproduce your observation so
> > that all window positioning is guaranteed to take place *before* the
> > clear screen action and still see the broken output?
>=20
> Hi Corinna,
>=20
> I have figured out how to reproduce it. There are two
> necessary conditions. No, three:
>=20
> 1. You must scroll the display all the way to the top
>    as far as you can before the clear screen is issued.
>=20
> 2. The scrollback history must be full. I.e., this
>    won't happen in a fresh cmd.exe window. First, print
>    thousands of lines of stuff to make the buffer "tall".
>    This is why  it only started happening to me after some
>    amount of testing; I had filled the buffer.
>=20
> 3. It's probably a necessary condition that there is additional
>    output immediately after the clear screen (such as the
>    programming language prompt being printed), because
>    the console scrolls to bottom on any output.
>=20
> I'm not sure if these are sufficient, but they seem to be
> on my end.

I could reproduce this now and I think I have fixed it.

There's still a problem with the position of the scrollbars in certain
scenarios where they are off by about one window size.  I added a FIXME
comment.

I have to admit I'm very puzzled that neither SetConsoleWindowInfo
nor the subsequent SetConsoleCursorPosition automatically set the
scrollbars correctly.  That's what I would expect, naively.

If anybody knows how to fix the scrollbar position in a Windows console
without moving the window contents around, please help.


Thanks,
Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

--3MwIy2ne0vdjdPXF
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=yraG
-----END PGP SIGNATURE-----

--3MwIy2ne0vdjdPXF--

- Raw text -