From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#23871: 25.1.50; Undo unexpectedly leads to blank buffer Date: Tue, 05 Jul 2016 23:00:25 +0300 Message-ID: <83a8hvonxi.fsf@gnu.org> References: <83h9cavdgj.fsf@gnu.org> <87poqyy2tc.fsf@metalevel.at> <87vb0qqrkz.fsf@russet.org.uk> <87h9c9zx75.fsf@metalevel.at> <834m89vmyv.fsf@gnu.org> <878txlsbdb.fsf@russet.org.uk> <87furtccdv.fsf@metalevel.at> <877fd5q9te.fsf@russet.org.uk> <83bn2gtruk.fsf@gnu.org> <87k2h37pvb.fsf@russet.org.uk> <87zipz223y.fsf@metalevel.at> <87a8hzkqp2.fsf@russet.org.uk> <87d1mv9gqm.fsf@metalevel.at> <8760smricr.fsf@russet.org.uk> <878txiha1g.fsf@metalevel.at> <87wpl2pj1u.fsf@russet.org.uk> <87shvqbcr0.fsf@metalevel.at> <83oa6dpiwz.fsf@gnu.org> <83mvlwnit1.fsf@gnu.org> <87furnj28o.fsf@metalevel.at> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1467749010 32097 80.91.229.3 (5 Jul 2016 20:03:30 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 5 Jul 2016 20:03:30 +0000 (UTC) Cc: 23871@debbugs.gnu.org, phillip.lord@russet.org.uk To: Markus Triska Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Tue Jul 05 22:03:19 2016 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bKWYx-0007Sb-1e for geb-bug-gnu-emacs@m.gmane.org; Tue, 05 Jul 2016 22:03:19 +0200 Original-Received: from localhost ([::1]:57809 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKWYt-0002nb-2I for geb-bug-gnu-emacs@m.gmane.org; Tue, 05 Jul 2016 16:03:15 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:37878) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKWYl-0002nF-8m for bug-gnu-emacs@gnu.org; Tue, 05 Jul 2016 16:03:08 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKWYg-0001E6-QD for bug-gnu-emacs@gnu.org; Tue, 05 Jul 2016 16:03:06 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:54527) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKWYg-0001Dx-Ll for bug-gnu-emacs@gnu.org; Tue, 05 Jul 2016 16:03:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1bKWYg-00059q-CE for bug-gnu-emacs@gnu.org; Tue, 05 Jul 2016 16:03:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 05 Jul 2016 20:03:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 23871 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 23871-submit@debbugs.gnu.org id=B23871.146774893219754 (code B ref 23871); Tue, 05 Jul 2016 20:03:02 +0000 Original-Received: (at 23871) by debbugs.gnu.org; 5 Jul 2016 20:02:12 +0000 Original-Received: from localhost ([127.0.0.1]:38628 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bKWXo-00058V-Mg for submit@debbugs.gnu.org; Tue, 05 Jul 2016 16:02:12 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:46114) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bKWXk-00057w-8W for 23871@debbugs.gnu.org; Tue, 05 Jul 2016 16:02:07 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKWXb-0000Ub-5M for 23871@debbugs.gnu.org; Tue, 05 Jul 2016 16:01:59 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:51193) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKWWr-0008Rs-GO; Tue, 05 Jul 2016 16:01:09 -0400 Original-Received: from 84.94.185.246.cable.012.net.il ([84.94.185.246]:3546 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1bKWWn-0006iF-Co; Tue, 05 Jul 2016 16:01:08 -0400 In-reply-to: <87furnj28o.fsf@metalevel.at> (message from Markus Triska on Tue, 05 Jul 2016 21:47:51 +0200) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:120463 Archived-At: > From: Markus Triska > Cc: 23871@debbugs.gnu.org, phillip.lord@russet.org.uk > Date: Tue, 05 Jul 2016 21:47:51 +0200 > > In some cases, I would prefer if the window displayed said line at > its center (instead of at its top). I thought about this, and doing so is very problematic. Many of these cases are when a large change happens in a continuation line which originally contained the window-start. When such a change happens, the display engine cannot know whether the result will be a continued line or a short line that doesn't need to be continued. The current code plays it safe and assumes it will still be continued, and in that case you don't want the recentering, because it would be unexpected. Detecting the special case where the remaining line is short enough to nod need continuation would need significantly more code, with special cases for invisible text, images, large fonts etc., all of which could take a line that has just a few character positions and make it need continuation lines. So I decided this minor issue isn't worth the hassle.