Bug#1070730: libglib2.0-0: broken ibus-mozc (japanese input) in GTK programs

[unfathomable18 at protonmail.com]

Package: libglib2.0-0
Version: 2.74.6-2+deb12u1
Severity: important
Tags: l10n

Dear Maintainer,

   * What led up to the situation?

Latest upgrade from 2.74.6-2 to 2.74.6-2+deb12u1 broke input of Japanese characters GTK programs (such as firefox, gedit etc).

Currently using ibus-mozc for Japanese input. The packages and versions are `ibus 1.5.27-5` and `ibus mozc 2.28.4715.102+dfsg-2.2`.

The mozc input method allows input of normal alphabet characters (direct input), and that is unaffected. When switching to input of Japanese characters (e.g. Hiragana), the input widget (in which you select word candidates) appears, but the selected text does not register as text input.

QT programs seem not to be affected. Japanese input is possible on those. Copying Japanese text from QT programs to GTK ones is also possible.


   * What exactly did you do (or not do) that was effective (or
     ineffective)?

The following did NOT work:
 - just restarting the system,
 - using im-config to reset input method configuration, and restarting;
 - stopping and restarting ibus;
 - removing and reinstalling ibus, ibus-mozc etc.

Reverting libglib2.0 and related packages from the current version (2.74.6-2+deb12u1) to the previous version (2.74.6-2) solved the problem. In particular, the command used was:
```sudo apt install libglib2.0-dev:amd64=2.74.6-2 libglib2.0-bin:amd64=2.74.6-2 libglib2.0-dev-bin:amd64=2.74.6-2 libglib2.0-0:amd64=2.74.6-2 libglib2.0-0:i386=2.74.6-2 libglib2.0-data:all=2.74.6-2```

This was confirmed multiple times (upgrading and downgrading a couple of times). When the packages are upgraded and the system is not reset, the input continues to work, but stops working after a reset.

Thus the problem seems to be in the newest version (2.74.6-2+deb12u1) of ibglib2.0-0 and related packages.


Thank you for your time.