I never experienced something like this before I upgrade to macOS sierra a few days ago. At first, I didn't notice it, but after a while, it becomes annoying as hell.
After selected a window from mission control, or just dismiss it (press
esc), it just lost focus of Finder and switch to another random apps (Skype, Chrome, XCode, blah blah...)
How to fix this?
This not only happened to Finder, but System Preference and sublimeText as well. Probably more apps might affected by this issue. But some apps (xcode, skype, chrome...) are not affected. I'm so confused....
Update 2: I've found the reason, but it's not satisfied me!
The reason for this lost focus is because I've set the option of Finder in dock assign to all desktop:
It won't lose focus anymore if I set it to a specific desktop. However, I'd like to have all Finder in all desktop as I used to it before :( still annoying.