URL: <https://savannah.gnu.org/bugs/?68273>
Summary: screen display corruption with U+200B ZERO WIDTH
SPACE (regression in v5)
Group: GNU Screen
Submitter: vinc17
Submitted: ven. 24 avril 2026 13:44:33
Category: None
Severity: 3 - Normal
Priority: 5 - Normal
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Unlocked
Release: 5.0.1
Fixed Release: None
Planned Release: None
Work Required: None
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Follow-up Comments:
-------------------------------------------------------
Date: ven. 24 avril 2026 13:44:33 By: Vincent Lefèvre <vinc17>
With GNU Screen v5, the U+200B ZERO WIDTH SPACE character (UTF-8: E2 80 8B)
can corrupt the screen display, as seen with Mutt.
Consider a mbox file containing twice the following message:
From [email protected] Fri Apr 24 08:48:52 2026
From: [email protected]
Subject: =?utf-8?Q?=E2=80=8B.abcdefghijklmnopqrstuvwxyz.1234567890?=
Date: Fri, 24 Apr 2026 08:48:27 +0200
(file "mbox" attached) and two possible muttc files:
* muttrc-1 with just the following line:
set arrow_cursor
* muttrc-2 with the following two lines:
set arrow_cursor
color index lightcyan black .
For the screenrc file, it is better to have "defbce on" for GNU Screen v4 (wih
my tests, it ensures a consistent background, but it does not have any effect
on how the text is positioned).
In a 80-column xterm, without GNU Screen or with GNU Screen v4, the following
commands
mutt -n -F muttrc-1 -f mbox
mutt -n -F muttrc-2 -f mbox
both give a correct output:
q:Quit d:Del u:Undel s:Save m:Mail r:Reply g:Group ?:Help
-> 1 N Apr 24 [email protected] ( 0K)
.abcdefghijklmnopqrstuvwxyz.1234567890
2 N Apr 24 [email protected] ( 0K)
.abcdefghijklmnopqrstuvwxyz.1234567890
---Mutt: mbox [Msgs:2 New:2
0.3K]---(date/date)-------------------------(all)---
(screenshot attached: xterm-screen-4.png).
Now, with GNU Screen v5 in a 80-column xterm:
* with "mutt -n -F muttrc-1 -f mbox":
q:Quit d:Del u:Undel s:Save m:Mail r:Reply g:Group ?:Help
-> 1 N Apr 24 [email protected] ( 0K)
.abcdefghijklmnopqrstuvwxyz.1234567892
N Apr 24 [email protected] ( 0K) .abcdefghijklmnopqrstuvwxyz.1234567890
---Mutt:
mbox [Msgs:2 New:2 0.3K]---(date/date)-------------------------(all)---
(screenshot attached: xterm-screen-5-1.png).
* with "mutt -n -F muttrc-2 -f mbox":
q:Quit d:Del u:Undel s:Save m:Mail r:Reply g:Group ?:Help
2 N Apr 24 [email protected] ( 0K) .abcdefghijklmnopqrstuvwxyz.1234567890
---Mutt:
mbox [Msgs:2 New:2 0.3K]---(date/date)-------------------------(all)---
(screenshot attached: xterm-screen-5-2.png).
I did my tests under Debian/unstable (for most packages) with the Debian
packages
* screen 4.9.1-3.1
* screen 5.0.1-1.1
_______________________________________________________
File Attachments:
Name: xterm-screen-5-2.png Size: 1,5kio
<https://file.savannah.gnu.org/file/xterm-screen-5-2.png?file_id=58506>
Name: xterm-screen-5-1.png Size: 1,8kio
<https://file.savannah.gnu.org/file/xterm-screen-5-1.png?file_id=58505>
Name: xterm-screen-4.png Size: 1,5kio
<https://file.savannah.gnu.org/file/xterm-screen-4.png?file_id=58504>
Name: mbox Size: 336o
<https://file.savannah.gnu.org/file/mbox?file_id=58503>
AGPL NOTICE
These attachments are served by Savane. You can download the corresponding
source code of Savane at
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