Accented characters missing on all browsers

At some point all browsers in my PC started to refuse showing accented characters (e.g. è) when the correct keys are pressed (first ` then e). This started happening before reinstalling the OS (Ubuntu Studio 22.04). Reinstalling the system, which came about for other reasons, did not help.

This problem was specific to web browsers only, even though it affected all of them equally. Typing accented characters continued to work fine everywhere else, e.g. in Konsole and Libreoffice. For a while the workaround was to type those characters in Konsole and copy them over.

Soon enough, I had enough and started to search for a proper solution.

Running each browser from Konsole, or watching ~/.xsession-errors, Chrome and Firefox produced different warning messages each time I tried to type an accented character:

$ tail -f ~/.xsession-errors
(google-chrome-stable:14941): Gdk-WARNING **: 15:19:37.785: gdk_window_set_user_time called on non-toplevel
** (firefox:2091768): WARNING **: 15:19:57.550: Error converting text from IM to UTF-8: Invalid byte sequence in conversion input

Searching for the warning from Chrome message, there are very few matching posts. This one suggested to unsetting the GTK_IM_MODULE variable, which I had set to xim:

$ echo $GTK_IM_MODULE
xim
$ unset GTK_IM_MODULE

This didn’t seem to help, at least not without restarting Chrome. A permanent solution could be to either fix xim or prevent the GTK_IM_MODULE variable from pointing to xim at all.

The variable seems to be set in /usr/share/im-config/data/80_kinput2.rc which is part of the im-config package.

To get a better idea of what xim was doing, I run im-config -a -s (without changing anything). This suggested I had manually selected xim via ~/.xinputrc and indeed that as the case, although this looks like the config was generated rather than manually created by me:

$ cat .xinputrc 
# im-config(8) generated on Sun, 24 Apr 2016 07:53:00 +0200
run_im xim
# im-config signature: 29c43083ff25c566c8c3ff6659294e6c  -

$ ls -l .xinputrc
-rw-rw-r-- 1 coder coder 130 Apr 24  2016 .xinputrc

Considering this config dates back to a long long time ago, I removed it and restarted the desktop to see if that would help... and it did!

While search for related posts I also found a tangentially related hint to run dpkg-reconfigure locales and add es_ES.UTF-8 (and/or others as desired) as a supported locale/s for the system (and regenerate them).

And then I remembered the System Notification Helper popup message telling me that Language support is incomplete, additional packages are required. Since I was feeling generous and this only takes about 120 MB of disk space, I just installed the missing packages:

# apt install $(check-language-support)
The following NEW packages will be installed:
  hunspell-en-au hunspell-en-ca hunspell-en-gb hunspell-en-us
  hunspell-en-za hyphen-en-ca hyphen-en-gb hyphen-en-us
  libreoffice-help-common libreoffice-help-en-gb
  libreoffice-help-en-us libreoffice-l10n-en-gb
  libreoffice-l10n-en-za mythes-en-au mythes-en-us
  thunderbird-locale-en-gb thunderbird-locale-en-us