Active keyboard layout affecting modifier keys functionality

I was using alt+shift+space and in russian keyboard layout it's was working not correctly. English keyboard layout posses correct behaviour.

https://youtu.be/Gof5WoqHjSk
[infolog.txt](https://github.com/beyond-all-reason/spring/files/13748497/infolog.txt)

Start by reproducing the reported alt+shift+space behavior with English and Russian keyboard layouts, using the linked video and infolog.txt as reference. Done means the modifier-key behavior is consistent across both layouts, with a regression check for the reported input sequence.

Written by the indexing model from the issue text.