> It's never the terminal emulator (whether GNOME Terminal or any other
terminal app) that decides what to print on a backspace keypress. The
only thing it does is that it tells over the tty line that the backspace
key has been pressed.
Makes sense. However, the user thinks of gnome-terminal because that's
what he runs...
> If your input method cannot generate the symbols you need, and you
need to press backspace as a workaround to get that, moreover, you need
to rely on one particular behavior of backspace, then I'd argue that
it's all the fault of your input method, it should be able to produce
straight away whatever you wish to end up with.
Unfortunately that's not always possible. Please take a look at the wiki
page under [1]. With complex writing systems there's more than one way
to write a word which look 'correct' on the screen, but the order of the
code points is different [2]. Not very good if you search for that word.
Therefore Keyman allows to define keyboards that can auto-correct words
so that you end up with the same order of the code points regardless
which way you type [3]. And that requires to replace some codepoints
typed previously.
> Maybe the bug you _really_ wanted to report is that gnome-terminal
doesn't use the "surrounding text" feature of input methods?
That would be nice to have but until then it would be good to have
backspace working properly. But as you wrote in an earlier comment that
has nothing to do with gnome-terminal...
[1] https://github.com/keymanapp/keyman/wiki/Backspace-and-cluster-deletion
[2] https://www.sil.org/resources/archives/91817
[3] https://help.keyman.com/keyboard/khmer_angkor/1.0.7/KAK_Documentation_EN.pdf
** Also affects: bash (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2051371
Title:
Backspace in gnome-terminal often deletes cluster
Status in bash package in Ubuntu:
New
Status in gnome-terminal package in Ubuntu:
New
Bug description:
If I have ខែ្ (U+1781 U+17c2 U+17d2) in the terminal and press
backspace, the first backspace deletes U+17c2 U+17d2 so that I'm left
with ខ (U+1781). Instead it should only delete the last codepoint,
U+17d2.
If I have ខែ (U+1781 U+17c2) a backspace deletes only U+17c2,
similarly if I have ខ្ (U+1781 U+17d2) where the backspace deletes
U+17d2.
Further investigations show that backspace often deletes the entire
cluster, i.e. diacritic(s) plus the base character, for example with
x̣́ (U+0078 U+0301 U+0323) where a backspace deletes all three
codepoints.
gnome-terminal should only delete the last codepoint [1].
A real live example where this behavior is problematic is when using
ibus-keyman with the Khmer Angkor keyboard [2]. When typing xEjmr the
expected output is ខ្មែរ (U+1781 U+17d2 U+1798 U+17c2 U+179a). Keyman
does some reordering while typing to put the codepoints in a
standardized order. Because gnome-terminal lacks support for
surrounding text, the codepoints have to be deleted by emitting
several backspace keypresses. Because of the deletion of the cluster
the result in gnome-terminal is ្មែរ (U+17d2 U+1798 U+17c2 U+179a).
[1] https://github.com/keymanapp/keyman/wiki/Backspace-and-cluster-deletion
[2] https://github.com/keymanapp/keyman/issues/10481
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: gnome-terminal 3.44.0-1ubuntu1 [modified:
usr/libexec/gnome-terminal-server]
ProcVersionSignature: Ubuntu 6.5.0-14.14~22.04.1-generic 6.5.3
Uname: Linux 6.5.0-14-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Jan 26 12:21:42 2024
InstallationDate: Installed on 2022-04-12 (653 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Beta amd64
(20220329.1)
SourcePackage: gnome-terminal
UpgradeStatus: No upgrade log present (probably fresh install)
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