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

[daanturo]

> 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.
 
Hello,
 
I can't find commit 1404e16975 in Emacs' master tree, but even when having IM 
disabled via `(setq pgtk-use-im-context-on-new-connection nil)` in init.el, 
Emacs is unable to recognize any Super-modified keys.
 
It's reproducible in `emacs -q` then `(pgtk-use-im-context nil)`.
 
I'm on Emacs master (8f3e0ed2b99b9b2ad42693cab2b3c0c291e3c3d0).
 
--  
Daanturo.