Hi Marc, great to hear, thanks for working on these issues!
I assume that is also the issue that I described here (dont be able to switch back to cubase from another application when the cubase video window is on fullscreen mode)?
Cubase 13.0.30 bug when switiching between windows
I have also found a problem with window-handling when I drag&drop an audiofile from the explorer into my timeline:
Windows Explorer is in foreground and focussed → I drag&drop the audiofile into the timeline → Cubase does not come into focus when it shows the “import options” window. Also I can’t just ALT+TAB and switch to Cubase (nothing happens when I do that), I have to ALT+TAB to the “import-options” window (which in addition is always at the very end of the row of opened windows in the “ALT+TAB” menu).
this behavior was already changed with the Cubase 13.0.30 update. Only the window you are activating (+ maybe popups and always on top windows) should come into foreground.
→ yes, switching back from another application to the project window, the mixer or another cubase window works on my system as long as I don’t have the cubase video window in fullscreen mode (on a second screen) 
My system: Win 11 and Cubase 13.0.30