bug#53200: 29.0.50; C-S-u shortcut fails with 'PGTK' enable

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Campbell Barton <ideasman42@gmail.com> writes:

> With PGTK enabled (--with-pgtk) the following occurs:
>
> - Press C-S-u
> - Press a
>
> The character 'a' is entered.
>
> Without PGTK enabled, the following occurs:
>
> - Press C-S-u
> - Press a
>
> The character 'aaaa' is entered 4x.
>
> Note that PGTK seems to swallow this binding, since it's not possible to
> check what the shortcut does by pressing:
>
> C-H, K, C-S-u
>
> Which reports without PGTK: (universal-argument)

This has been reported at least twice already.  Someone should volunteer
to find and merge all those bugs, but in short: most GTK input method
modules stupidly eat the shift modifier, and the only workaround is to
disable the use of GTK input methods by setting `pgtk-use-im-context' to
nil.

This is really a bug in the various input modules and should be reported
to their developers instead instead.  If you're using ibus, for example,
complain to ibus developers about their IM context not setting the shift
modifier mask in an event sent by the filter.

Alternatively, you can use the regular X build, which is a much superior
experience over the PGTK port as long as you're not using Wayland.

Thanks, and please let us know about the progress of your complaining to
the IM module developers.  It would be greatly appreciated.