bug#23879: visual-line-mode produces erratic behaviour with text properties

bug#23879: visual-line-mode produces erratic behaviour with text properties

[Paul Rankin]

Enabling visual-line-mode and adding line-prefix and wrap-prefix properties to a long paragraph of text produces erratic navigational behaviour.

To reproduce:

1. $ emacs -Q

2. insert a long paragraph of text
M-: (url-insert-file-contents "https://gist.githubusercontent.com/rnkn/d5987c3495901e4950782f6648846e4e/raw/c22074e8f0940f6ec9c8b729f04567dc50664823/loren-ipsum.txt")

3. turn on visual line mode
M-: (visual-line-mode 1)

4. add text properties
M-: (add-text-properties (point-min) (point-max) '(line-prefix (space :align-to 10) wrap-prefix (space :align-to 10)))

5. C-n past window height.

Expected results:

Navigation should continue by visual line.

Actual results:

Navigational behaviour becomes erratic. Point will no long move with visual lines, instead jumping to different columns. This is more pronounced with a window 80 columns or less.

Configuration:

GNU Emacs 24.5.1 (x86_64-apple-darwin15.5.0, NS apple-appkit-1404.47) of 2016-06-26

Configured using:
 `configure --disable-dependency-tracking --disable-silent-rules
 --enable-locallisppath=/usr/local/share/emacs/site-lisp
 --infodir=/usr/local/Cellar/emacs/24.5/share/info/emacs
 --prefix=/usr/local/Cellar/emacs/24.5 --with-xml2 --without-dbus
 --without-gnutls --with-ns --disable-ns-self-contained'

OS X 10.11.4 (15E65)

MacBook Pro (Retina, 15-inch, Mid 2014)
2.2 GHz Intel Core i7
16 GB 1600 MHz DDR3
Intel Iris Pro 1536 MB

-- 
Paul W. Rankin
www.paulwrankin.com

bug#23879: visual-line-mode produces erratic behaviour with text properties

[Eli Zaretskii]

> From: Paul Rankin <hello@paulwrankin.com>
> Date: Fri, 01 Jul 2016 18:33:48 +1000
> 
> 1. $ emacs -Q
> 
> 2. insert a long paragraph of text
> M-: (url-insert-file-contents "https://gist.githubusercontent.com/rnkn/d5987c3495901e4950782f6648846e4e/raw/c22074e8f0940f6ec9c8b729f04567dc50664823/loren-ipsum.txt")
> 
> 3. turn on visual line mode
> M-: (visual-line-mode 1)
> 
> 4. add text properties
> M-: (add-text-properties (point-min) (point-max) '(line-prefix (space :align-to 10) wrap-prefix (space :align-to 10)))
> 
> 5. C-n past window height.
> 
> Expected results:
> 
> Navigation should continue by visual line.
> 
> Actual results:
> 
> Navigational behaviour becomes erratic. Point will no long move with visual lines, instead jumping to different columns. This is more pronounced with a window 80 columns or less.

Initial investigation indicates that this is a very old problem: I see
it in Emacs 23.1, which is when visual-line-mode was introduced.

bug#23879: visual-line-mode produces erratic behaviour with text properties

[Eli Zaretskii]

> Date: Fri, 01 Jul 2016 12:37:31 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 23879@debbugs.gnu.org
> 
> Initial investigation indicates that this is a very old problem: I see
> it in Emacs 23.1, which is when visual-line-mode was introduced.

Indeed, a very old bug, now fixed on the master branch.

Thanks.

bug#23879: closed (Re: bug#23879: visual-line-mode produces erratic behaviour with text properties)

[Paul Rankin]

I can confirm the issue appears fixed on HEAD but not devel (25.0.95).

Is there a way I can go about tracking the version in which this fix will be included?

bug#23879: closed (Re: bug#23879: visual-line-mode produces erratic behaviour with text properties)

[Eli Zaretskii]

> From: Paul Rankin <hello@paulwrankin.com>
> Date: Sun, 03 Jul 2016 16:49:04 +1000
> 
> I can confirm the issue appears fixed on HEAD but not devel (25.0.95).

I fixed this only on master, since the bug is very old.

> Is there a way I can go about tracking the version in which this fix will be included?

Not before 25.2.

bug#23879: closed (Re: bug#23879: visual-line-mode produces erratic behaviour with text properties)

[Glenn Morris]

Paul Rankin wrote:

> I can confirm the issue appears fixed on HEAD but not devel (25.0.95).
>
> Is there a way I can go about tracking the version in which this fix
> will be included?

It's easy for people closing bugs to include the version information
when they do so, in a way that debbugs can pick up.
(But whether Emacs sticks to that release schedule is another matter.)