Pressing ? and then x gives back broken Emacs

[DamienCassou]

1. start emacs -Q
2. evaluate the following in the scratch buffer

   (require 'package)
   (add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))
   (package-initialize)
   (package-refresh-contents)
   (package-install 'ace-window)

3. Create some frames: C-x 3 C-x 2
4. Type M-x ace-window RET ? x 2

ace-windows is now terminated, but the Emacs syntax highlighting colors are not back:

[abo-abo]

Thanks, please test.

[abo-abo]

Thanks, please test.

[DamienCassou]

It works fine, thank you.