If your editor window is unfocused, you can click on visible components and interact with the editor. It stays out of focus for a few of these clicks.
Eventually the windows comes into focus.
Occurs on MacOS. Does NOT appear to be reproducible on Windows.

1. Create a new unity project.
2. Put an external program window over the Unity Editor and focus it so it's partially covering the editor. (i.e. Web Browser)
3. Click on a visible editor tab or button.

Expected result: Window comes into focus, responds to what you clicked on.
Actual result: Window stays out of focus, but still responds to what you clicked on.

Note:
- Tested on Mac and Windows.
- Usually focuses on the 2nd or 3rd interaction with the editor window.
- Video example of this occurring in comments.

Reproducible in 2020.1.0a15
Not reproducible in 2019.3.0b12, 2020.1.0a12, 2020.1.0a14