From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#5998: 23.1.96; Breadcrumbs defeat C-u 1 C-v in Info Date: Tue, 06 Sep 2016 18:02:05 +0300 Message-ID: <83mvjlax76.fsf@gnu.org> References: <83iq7k4tcl.fsf@gnu.org> <9B4B02341F5B4DDEAFD1EB51D850CC00@us.oracle.com> <83eg4ycs7e.fsf@gnu.org> <87shte6t9p.fsf@mail.linkov.net> Reply-To: Eli Zaretskii NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1473175367 4083 195.159.176.226 (6 Sep 2016 15:22:47 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 6 Sep 2016 15:22:47 +0000 (UTC) Cc: ahyatt@gmail.com, 5998@debbugs.gnu.org To: Juri Linkov Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Tue Sep 06 17:22:40 2016 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bhICp-0008Mn-7T for geb-bug-gnu-emacs@m.gmane.org; Tue, 06 Sep 2016 17:22:35 +0200 Original-Received: from localhost ([::1]:34319 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhICm-0003OR-KM for geb-bug-gnu-emacs@m.gmane.org; Tue, 06 Sep 2016 11:22:32 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:58468) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhHu0-00039a-5W for bug-gnu-emacs@gnu.org; Tue, 06 Sep 2016 11:03:12 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bhHtu-0006Ce-2t for bug-gnu-emacs@gnu.org; Tue, 06 Sep 2016 11:03:07 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:53727) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhHtt-0006Ca-VS for bug-gnu-emacs@gnu.org; Tue, 06 Sep 2016 11:03:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1bhHtt-0008Gx-M4 for bug-gnu-emacs@gnu.org; Tue, 06 Sep 2016 11:03:01 -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, 06 Sep 2016 15:03:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 5998 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 5998-submit@debbugs.gnu.org id=B5998.147317416631772 (code B ref 5998); Tue, 06 Sep 2016 15:03:01 +0000 Original-Received: (at 5998) by debbugs.gnu.org; 6 Sep 2016 15:02:46 +0000 Original-Received: from localhost ([127.0.0.1]:51439 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bhHta-0008GL-FY for submit@debbugs.gnu.org; Tue, 06 Sep 2016 11:02:46 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:39075) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bhHtT-0008G4-H6 for 5998@debbugs.gnu.org; Tue, 06 Sep 2016 11:02:39 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bhHtJ-00064N-S4 for 5998@debbugs.gnu.org; Tue, 06 Sep 2016 11:02:30 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:55728) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bhHtA-00061L-04; Tue, 06 Sep 2016 11:02:16 -0400 Original-Received: from 84.94.185.246.cable.012.net.il ([84.94.185.246]:4120 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1bhHt8-000771-12; Tue, 06 Sep 2016 11:02:14 -0400 In-reply-to: <87shte6t9p.fsf@mail.linkov.net> (message from Juri Linkov on Mon, 05 Sep 2016 22:28:18 +0300) 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:123004 Archived-At: > From: Juri Linkov > Cc: Andrew Hyatt , 5998@debbugs.gnu.org, drew.adams@oracle.com > Date: Mon, 05 Sep 2016 22:28:18 +0300 > > > (But the original problem with > > scrolling a window that starts with invisible text followed by an > > overlay with an after-string -- that problem still exists.) > > Or there is no bug at all: with invisible text followed by an overlay > with an after-string you can't put point to the beginning of the Info > buffer - probably for a reason. OTOH, using more reasonable ‘display’ > allows point to move to the top of the window, so perhaps this is why > scrolling works in the latter case but doesn't work in the former one. The actual problem is that an "empty" overlay (i.e. overlay that hides no buffer positions) with a before-string or after-string at the beginning of the window exposes a flaw in the method the Emacs display engine determines a window-start position: it is specified by a buffer position. That makes the actual window-start on display ambiguous, since both the overlay string and the buffer position after it have the same value. If the string also includes a newline, it defeats the algorithm for scrolling a window by N lines, which just goes to the window-start point, and then moves forward/back by those N lines. In particular, if N = 1, the buffer position after the move is unchanged, and the scroll will appear to have not happened. I have a working patch for fixing this, but it sometimes requires to invoke the scroll command twice, so I'm trying to find a better fix. If I won't find it, I will commit what I have, because it's an improvement.