bug#27014: 26.0.50; auto-hscroll-mode and tabulated-list-mode

bug#27014: 26.0.50; auto-hscroll-mode and tabulated-list-mode

[Stephen Berman]

0. emacs -Q
1. Set auto-hscroll-mode to `current-line'.
2. Visit a buffer that uses tabulated-list-mode, e.g. Buffer Menu (C-x
   C-b), Package Menu (M-x list-packages), Proced (M-x proced), making
   sure that the buffer contains at least one truncated line and a line
   below it.
3. Advance point along the truncated line (e.g. by repeating C-f or M-f
   or with C-e).
=> When point gets within hscroll-margin columns of the right window
   edge (or further), instead of the current line being scrolled, the
   one below it is.

(In addition, with Proced, the header line is also scrolled, but that
seems to be a Proced bug, since that also happens when auto-hscroll-mode
is set to t; and with Buffer Menu or Package Menu the header line does
not scroll with either setting of auto-hscroll-mode.)

In GNU Emacs 26.0.50 (build 14, x86_64-pc-linux-gnu, GTK+ Version 3.22.8)
 of 2017-05-21 built on rosalinde
Repository revision: 08212929ba7052883bd506be320dfaaae5b68970
Windowing system distributor 'The X.Org Foundation', version 11.0.11901000

Configured using:
 'configure 'CFLAGS=-Og -g3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK3 X11

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

bug#27014: 26.0.50; auto-hscroll-mode and tabulated-list-mode

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Date: Mon, 22 May 2017 01:06:50 +0200
> 
> 0. emacs -Q
> 1. Set auto-hscroll-mode to `current-line'.
> 2. Visit a buffer that uses tabulated-list-mode, e.g. Buffer Menu (C-x
>    C-b), Package Menu (M-x list-packages), Proced (M-x proced), making
>    sure that the buffer contains at least one truncated line and a line
>    below it.
> 3. Advance point along the truncated line (e.g. by repeating C-f or M-f
>    or with C-e).
> => When point gets within hscroll-margin columns of the right window
>    edge (or further), instead of the current line being scrolled, the
>    one below it is.

Ah, yes: the header line and its confusing effect on the display
iterator geometry.  Should be fixed now.

> (In addition, with Proced, the header line is also scrolled, but that
> seems to be a Proced bug

It looks like a feature: Proced scrolls the header line to keep the
column headings in sync with the hscroll.

bug#27014: 26.0.50; auto-hscroll-mode and tabulated-list-mode

[Stephen Berman]

On Mon, 22 May 2017 21:19:18 +0300 Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Stephen Berman <stephen.berman@gmx.net>
>> Date: Mon, 22 May 2017 01:06:50 +0200
>> 
>> 0. emacs -Q
>> 1. Set auto-hscroll-mode to `current-line'.
>> 2. Visit a buffer that uses tabulated-list-mode, e.g. Buffer Menu (C-x
>>    C-b), Package Menu (M-x list-packages), Proced (M-x proced), making
>>    sure that the buffer contains at least one truncated line and a line
>>    below it.
>> 3. Advance point along the truncated line (e.g. by repeating C-f or M-f
>>    or with C-e).
>> => When point gets within hscroll-margin columns of the right window
>>    edge (or further), instead of the current line being scrolled, the
>>    one below it is.
>
> Ah, yes: the header line and its confusing effect on the display
> iterator geometry.  Should be fixed now.

Confirmed, and thanks!

>> (In addition, with Proced, the header line is also scrolled, but that
>> seems to be a Proced bug
>
> It looks like a feature: Proced scrolls the header line to keep the
> column headings in sync with the hscroll.

Ah, hmm.  Doesn't seem all that helpful and was on first encounter
rather confusing, especially since other tabulated-list-based modes like
Buffer Menu and Package Menu don't do this.

Steve Berman

bug#27014: 26.0.50; auto-hscroll-mode and tabulated-list-mode

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: 27014@debbugs.gnu.org
> Date: Mon, 22 May 2017 23:23:39 +0200
> 
> > Ah, yes: the header line and its confusing effect on the display
> > iterator geometry.  Should be fixed now.
> 
> Confirmed, and thanks!

Closing.

> >> (In addition, with Proced, the header line is also scrolled, but that
> >> seems to be a Proced bug
> >
> > It looks like a feature: Proced scrolls the header line to keep the
> > column headings in sync with the hscroll.
> 
> Ah, hmm.  Doesn't seem all that helpful and was on first encounter
> rather confusing, especially since other tabulated-list-based modes like
> Buffer Menu and Package Menu don't do this.

Maybe they all should.