bug#53516: Buffer display issue with unicode characters on WSL2

bug#53516: Buffer display issue with unicode characters on WSL2

[Green, Marc E.]

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Hello,

I have a file with a single Unicode character in it: 🕯 (Unicode character CANDLE, codepoint 128367, #o372557, #x1f56f).

When I open this file via `emacs -Q` (with or without `-nw`) and hit `C-l`, the buffer display has issues. Namely, the character becomes invisible on that line, and instead somehow appears in the menu bar line (the top 'File,Edit,etc' menu bar line disappears). It's like the whole display gets shifted up 1 line. If I move the cursor left, I can see the original character, which is now being displayed 2 times in the buffer despite existing in the file only once.

In practice, this makes it very difficult to edit files that have unicode characters in them. For files that have many lines in them, this issue results in lines being visually duplicated. Selecting them via C-SPACE does fix the display issue, until I start navigating around the file again, which triggers the issue.

System: WSL2 running Ubuntu 20.04 on Windows 10

Thank you,
Marc

---


In GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.14)
of 2020-03-26, modified by Debian built on lcy01-amd64-020
System Description:     Ubuntu 20.04.3 LTS

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
'configure --build x86_64-linux-gnu --prefix=/usr
--sharedstatedir=/var/lib --libexecdir=/usr/lib
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Configured features:
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NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
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bug#53516: Buffer display issue with unicode characters on WSL2

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

"Green, Marc E." <marcgreen@wpi.edu> writes:

> I have a file with a single Unicode character in it: 🕯 (Unicode
> character CANDLE, codepoint 128367, #o372557, #x1f56f).

> When I open this file via `emacs -Q` (with or without `-nw`) and hit
> `C-l`, the buffer display has issues. Namely, the character becomes
> invisible on that line, and instead somehow appears in the menu bar
> line (the top 'File,Edit,etc' menu bar line disappears). It's like the
> whole display gets shifted up 1 line. If I move the cursor left, I can
> see the original character, which is now being displayed 2 times in
> the buffer despite existing in the file only once.

> In practice, this makes it very difficult to edit files that have
> unicode characters in them. For files that have many lines in them,
> this issue results in lines being visually duplicated. Selecting them
> via C-SPACE does fix the display issue, until I start navigating
> around the file again, which triggers the issue.

Does this still happen with Emacs 28 or 29?  The version of Emacs you're
using is very old, and uses Xft, which is known to have display issues
with glyphs that might be provided by color fonts.

Thanks.

bug#53516: [EXT] Re: bug#53516: Buffer display issue with unicode characters on WSL2

[Green, Marc E.]

It does not happen when I use emacs 29 with the `-Q` option. So, now I have some leads to look into - thanks!

And if it's worth anything, the issue persists at least through emacs 27.2.

-----Original Message-----
From: Po Lu [mailto:luangruo@yahoo.com] 
Sent: Tuesday, January 25, 2022 1:43 AM
To: Green, Marc E. <marcgreen@wpi.edu>
Cc: 53516@debbugs.gnu.org
Subject: [EXT] Re: bug#53516: Buffer display issue with unicode characters on WSL2

"Green, Marc E." <marcgreen@wpi.edu> writes:

> I have a file with a single Unicode character in it: 🕯 (Unicode 
> character CANDLE, codepoint 128367, #o372557, #x1f56f).

> When I open this file via `emacs -Q` (with or without `-nw`) and hit 
> `C-l`, the buffer display has issues. Namely, the character becomes 
> invisible on that line, and instead somehow appears in the menu bar 
> line (the top 'File,Edit,etc' menu bar line disappears). It's like the 
> whole display gets shifted up 1 line. If I move the cursor left, I can 
> see the original character, which is now being displayed 2 times in 
> the buffer despite existing in the file only once.

> In practice, this makes it very difficult to edit files that have 
> unicode characters in them. For files that have many lines in them, 
> this issue results in lines being visually duplicated. Selecting them 
> via C-SPACE does fix the display issue, until I start navigating 
> around the file again, which triggers the issue.

Does this still happen with Emacs 28 or 29?  The version of Emacs you're using is very old, and uses Xft, which is known to have display issues with glyphs that might be provided by color fonts.

Thanks.

bug#53516: [EXT] Re: bug#53516: Buffer display issue with unicode characters on WSL2

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

"Green, Marc E." <marcgreen@wpi.edu> writes:

> It does not happen when I use emacs 29 with the `-Q` option. So, now I
> have some leads to look into - thanks!

Thanks, what about Emacs 28?  I assume it's fixed there too.

bug#53516: Buffer display issue with unicode characters on WSL2

[Lars Ingebrigtsen]

Po Lu <luangruo@yahoo.com> writes:

>> It does not happen when I use emacs 29 with the `-Q` option. So, now I
>> have some leads to look into - thanks!
>
> Thanks, what about Emacs 28?  I assume it's fixed there too.

There wasn't any followup here in a month, so I assume that this fix
worked, and I'm closing this bug report.  (If this is still a problem,
Marc, please respond to the debbugs address and we'll reopen.)

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