Basj, OK, Thunderbird seems to be working OK since I disabled it in Groupy. But FileBack still doing very strange things: window disappears for 15 secs and re-appears, normal actions slow. Also when interacting with it, my Chrome window where I"m typing this, also disappears and reappears. That seems to ONLY happen when I'm interacting with FileBack and typing into a Chrome window (e.g. this reply). It looks like the 2 windows are somehow confused temporarily.&
BaliDave
Basj, Rebooting didn't help. Also after grouping Thunderbird windows, often things are not working there -- clicking on reply to a message, right clicking on some buttons, and even the top File menu. Sometimes I can regain functionality by ungrouping a Thunderbird window, but not consistently. This is a stopper for me since I spend a lot of my time in Thunderbird. I'd like to keep what Groupy brings but can't have it massively interfere with my activities. 
Basj, Thanks, but all looks fine in scf: sfc /scannow Beginning system scan. This process will take some time. Beginning verification phase of system scan. Verification 100% complete. Windows Resource Protection did not find any integrity violations. That's what I expected since I only moved to Win 10 version 1809 two weeks ago. Note that I only saw Chrome "do something funny" that one time, so I
Basj, Thanks, I just tried that but I still get the same behavior. Maybe rebooting might fix some of these? I don't reboot very often (weeks). Or any other ideas? (Interestingly as I'm typing this even my Chrome window is vanishing for a few seconds and then reappearing -- I've never seen this before, so I assume something about Groupy. I'm not doing anything Groupy-wise w Chrome either. Thanks
I just installed Groupy on my Win 10 x64 box. It's doing great. However one old app (FileBack PC 4.1) I have and still frequently use, looks to be somehow incompatible with it when Groupy is on (the window keeps disappearing, program response very slow, ...). Note that I am NOT trying to Group it with anything or even use Groupy with it -- I just want to use it "normally". I added it to the list of Application Exclusions, but still have the problem. Is there some