GNU bug report logs - #11857
large hscroll values mess up the display

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 11857 in the body.
You can then email your comments to 11857 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: bug-gnu-emacs <at> gnu.org
Subject: large hscroll values mess up the display
Date: Wed, 04 Jul 2012 11:15:50 -0700

I tried out large hscroll values and got messed
up displays.  The exact details vary, depending
on display and other parameters I don't understand.
In some cases, even hscroll values well under INT_MAX
caused problems, but these are harder to reproduce.

One way to easily reproduce the problem on Fedora 15
x86-64 with Emacs trunk bzr 108872 is to run
emacs -Q on an X display and type this:

C-u 1 0 0 0 0 0 0 0 0 0 0 C-x < SPC

That is, scroll by 10**10.  This results in a display
with <- in front of the first four lines, -> after
the first three lines, and semicolons in the start
of the first three lines.  It looks like this:

<-;                           ->
<-;                           ->
<-;                           ->
<-

Where "<-" and "->" denote the margin arrows.  This
is incorrect, as the display should look
like it does when scrolling by 100, namely, like this:

<-
<-
<-
<-

I also reproduced the problem with Emacs 23.3.1
(stock Ubuntu 12.04 x86) so this is not a new bug
nor is it restricted to 64-bit hosts.

Message #10 received at 11857-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 11857-done <at> debbugs.gnu.org
Subject: Re: bug#11857: large hscroll values mess up the display
Date: Thu, 05 Jul 2012 19:29:45 +0300

> Date: Wed, 04 Jul 2012 11:15:50 -0700
> From: Paul Eggert <eggert <at> cs.ucla.edu>
> 
> I tried out large hscroll values and got messed
> up displays.  The exact details vary, depending
> on display and other parameters I don't understand.
> In some cases, even hscroll values well under INT_MAX
> caused problems, but these are harder to reproduce.
> 
> One way to easily reproduce the problem on Fedora 15
> x86-64 with Emacs trunk bzr 108872 is to run
> emacs -Q on an X display and type this:
> 
> C-u 1 0 0 0 0 0 0 0 0 0 0 C-x < SPC
> 
> That is, scroll by 10**10.  This results in a display
> with <- in front of the first four lines, -> after
> the first three lines, and semicolons in the start
> of the first three lines.  It looks like this:
> 
> <-;                           ->
> <-;                           ->
> <-;                           ->
> <-
> 
> Where "<-" and "->" denote the margin arrows.  This
> is incorrect, as the display should look
> like it does when scrolling by 100, namely, like this:
> 
> <-
> <-
> <-
> <-
> 
> I also reproduced the problem with Emacs 23.3.1
> (stock Ubuntu 12.04 x86) so this is not a new bug
> nor is it restricted to 64-bit hosts.

Fixed in revisions 108879 and 108880 on the trunk.

I'm closing the bug; feel free to reopen if there are leftovers.

Thanks.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.