Subject: bug#42655: 27.1; iconify-frame on a Lucid build may stuck the frame

From: Eli Zaretskii <[email-masked]>
Date: Sat, 01 Aug 2020 21:53:26 +0300

> From: Tino Calancha <[email-masked]>
> Date: Sat, 01 Aug 2020 20:46:03 +0200
> Cc: paul eggert <[email-masked]>, stefan monnier <[email-masked]>,
>  [email-masked]
> 
> In a GUI session, with Emacs built with Lucid toolkit in a Linux machine,
> do:
> emacs -Q
> C-z
> ;; select again the window displaying the Emacs GUI
> -------------------------------------------------------------------------------
> 
> - You cannot insert characters in the *scratch* buffer.
> - Normal movement, for intance, `C-n' or `C-f' doesn't work.

If you now attach a debugger to Emacs, what does the backtrace show?