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

[Morgan Smith]

Hello,

I'd like to report that my super key stopped registering.  I 
suspected commit 1404e16975 caused it so I did a quick `git revert 
1404e16975` ontop of 807682de1e and that fixed it.

I'm running pgtk on wayland with (pgtk-use-im-context nil) 
(although that doesn't seem to affect this issue). 

Thanks,

Morgan