Close Expression Map Setup and Editor closes also

1- New project
2 - Add Track : Midi
3 - Double Click to create an event
4 - Open Editor
5 - Go to Expression Map Setup…
6 - Add Map
7 - Close Expression Map Setup and Editor closes also.

Cubase 8.0.10 Build 427 (64 bit)
Win 7 SP1 64 bit
Dual Monitor
Intel I7-3930K CPU

I confirm.

4- Open any Editor (Score, key, List …)
6- This step is not necessary

Actually the Editor window doesn’t close but looses focus, is sent backward and disappears behind the main project window.

Thanks for modifications of post.
Did not quite get your ‘looses focus’ point at first, because the effect was, as if the editor closes, but have experimented with resizing, annoyingly and coping much better (although went back to C7.5, for a minute and it was bliss, in comparison), so cheers!

NB: Have, observed, today, that this is also occurring when Project Notepad is opened, then closed: again a tad irritating!

After further investigation as of now, closing the following windows brings Project Window to front :

Expression Map Setup
Tempo Track