bug#51372: 27.2; Mouse face not cleared in some cases

bug#51372: 27.2; Mouse face not cleared in some cases

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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Increase the font size to something very large, like:

  ftcrhb:-ADBO-Source Code Pro-normal-normal-normal-*-167-*-*-*-m-0-iso10646-1 (#x3BD).

Then enter Info, find a hyperlink, resize the frame so that the
hyperlink is wrapped.  Occasionally, the mouse face will not be cleared
entirely, as in the attached screenshot.


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This happens in both 27.2, 28 and 29.  Thanks.

In GNU Emacs 27.2 (build 1, x86_64-redhat-linux-gnu, GTK+ Version 3.24.30, cairo version 1.17.4)
 of 2021-08-08 built on buildvm-x86-29.iad2.fedoraproject.org
Windowing system distributor 'The X.Org Foundation', version 11.0.12101002
System Description: Fedora 34 (Workstation Edition)

Recent messages:
Loading /usr/share/emacs/site-lisp/site-start.d/mercurial-site-start.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/protobuf-init.el (source)...done
Loading /usr/share/emacs/site-lisp/site-start.d/rpmdev-init.el (source)...done
For information about GNU Emacs and the GNU system, type C-h C-a.
Composing main Info directory...done
Mark saved where search started
<C-mouse-6> is undefined
<C-double-mouse-6> is undefined
<C-mouse-6> is undefined
Use +,-,0 for further adjustment [9 times]

Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
 --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
 --with-gpm=no --with-xwidgets --with-modules --with-harfbuzz
 --with-cairo --with-json build_alias=x86_64-redhat-linux-gnu
 host_alias=x86_64-redhat-linux-gnu CC=gcc 'CFLAGS=-DMAIL_USE_LOCKF -O2
 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches
 -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
 -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection'
 LDFLAGS=-Wl,-z,relro
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS
LIBSYSTEMD JSON PDUMPER GMP

Important settings:
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Info

Minor modes in effect:
  text-scale-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
/usr/share/emacs/site-lisp/lilypond-init hides /usr/share/emacs/site-lisp/site-start.d/lilypond-init

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
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text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote threads dbusbind
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xwidget-internal cairo move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 127973 8180)
 (symbols 48 7028 1)
 (strings 32 25958 2841)
 (string-bytes 1 929330)
 (vectors 16 11653)
 (vector-slots 8 149882 15214)
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bug#51372: 27.2; Mouse face not cleared in some cases

[Lars Ingebrigtsen]

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Po Lu <luangruo@yahoo.com> writes:

> Then enter Info, find a hyperlink, resize the frame so that the
> hyperlink is wrapped.  Occasionally, the mouse face will not be cleared
> entirely, as in the attached screenshot.

I'm unable to reproduce the problem (in Emacs 29).  Here's what I tried:

./src/emacs -geometry -0+0  -Q  -fn "DejaVu Sans Mono-40"
M-x info RET

I scrolled down to the stand-alone info and hovered the mouse:


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When I moved the mouse away:


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-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#51372: 27.2; Mouse face not cleared in some cases

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> I'm unable to reproduce the problem (in Emacs 29).

I also can't reproduce this here, using:

    ./src/emacs -Q -fn "Ubuntu Mono-40"

Same recipe as Lars.

In GNU Emacs 29.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version
3.24.24, cairo version 1.16.0)
 of 2021-10-24 built on joffe
Repository revision: aea4af5119fdf130f1df7190478a23c6777f92a2
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
WEBP X11 XDBE XIM XPM GTK3 ZLIB

bug#51372: 27.2; Mouse face not cleared in some cases

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> I scrolled down to the stand-alone info and hovered the mouse:
>
>
>
>
> When I moved the mouse away:

Hmm... Try resizing the frame so the 'n' in "stand-alon" gets wrapped,
but no other character can take its place.

Thanks.

bug#51372: 27.2; Mouse face not cleared in some cases

[Lars Ingebrigtsen]

Po Lu <luangruo@yahoo.com> writes:

> Hmm... Try resizing the frame so the 'n' in "stand-alon" gets wrapped,
> but no other character can take its place.

I tried resizing the window like that now, but I was still unable to see
the glitch.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#51372: 27.2; Mouse face not cleared in some cases

[Eli Zaretskii]

> Date: Sun, 24 Oct 2021 19:21:05 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Increase the font size to something very large, like:
> 
>   ftcrhb:-ADBO-Source Code Pro-normal-normal-normal-*-167-*-*-*-m-0-iso10646-1 (#x3BD).
> 
> Then enter Info, find a hyperlink, resize the frame so that the
> hyperlink is wrapped.  Occasionally, the mouse face will not be cleared
> entirely, as in the attached screenshot.

I don't understand what situation needs to be created to see the
problem.  The screenshot shows just a handful of characters, and a
single incomplete screen line, so I cannot figure out what follows it
nor what kind of "hyperlink" is that.  I also don't understand what
should have caused the mouse face to be cleared (but didn't, according
to your report).

So please provide a more detailed recipe.

Thanks.

bug#51372: 27.2; Mouse face not cleared in some cases

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Eli Zaretskii <eliz@gnu.org> writes:

> I don't understand what situation needs to be created to see the
> problem.  The screenshot shows just a handful of characters, and a
> single incomplete screen line, so I cannot figure out what follows it
> nor what kind of "hyperlink" is that.  I also don't understand what
> should have caused the mouse face to be cleared (but didn't, according
> to your report).

I meant to say that part of the mouse face background would remain, even
after the cursor was moved out of one of the links in Info.

But this could be a machine specific problem, because today I couldn't
reproduce the issue on another machine running the same software.

Thanks.

bug#51372: 27.2; Mouse face not cleared in some cases

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: 51372@debbugs.gnu.org
> Date: Tue, 26 Oct 2021 10:16:47 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I don't understand what situation needs to be created to see the
> > problem.  The screenshot shows just a handful of characters, and a
> > single incomplete screen line, so I cannot figure out what follows it
> > nor what kind of "hyperlink" is that.  I also don't understand what
> > should have caused the mouse face to be cleared (but didn't, according
> > to your report).
> 
> I meant to say that part of the mouse face background would remain, even
> after the cursor was moved out of one of the links in Info.
> 
> But this could be a machine specific problem, because today I couldn't
> reproduce the issue on another machine running the same software.

Try disabling optimizations in the video driver on the machine where
you see this.

So should we close this bug for now?

bug#51372: 27.2; Mouse face not cleared in some cases

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Eli Zaretskii <eliz@gnu.org> writes:

> Try disabling optimizations in the video driver on the machine where
> you see this.

I think I've found the actual problem, at least for me: the problem
manifests when using Xwayland, but not when running under plain X.Org.

The other machine I used to test couldn't run Wayland due to the
presence of incompatible graphics drivers.

So this is indeed quite an odd bug.

> So should we close this bug for now?

Maybe it should be left around, in case someone else experiences it and
can shed more light on why it happens?

Thanks.