Hi again @fingew,
I was able to replicate the issue on my side. The problem seems to happen only when the Overview sub-window is active and a configuration is loaded. If a configuration hasn't been loaded, or if this window is inactive, closed or detached, the alt + space keyboard shortcut works normally.
I believe this is a bug. I will communicate this issue to the Config Tools team so it can get fixed.
Thank you for reporting it.
BR,
Edwin.