Steps to reproduce:

1. Open attached project
2. Build and run for Mac Standalone
3. Switch to fullscreen by clicking the green circle in the top-left
4. Open 'Mission Control' (click F3 button)
5. Drag any other running app to the same window where game is
6. Notice the Unity build does not adjust accordingly, only renders half of the windows (see attached video for repro)

Note: If at step 3, you go fullscreen with other app, and drag Unity build as a second one, Unity build simply doesn't render anything (window stays black).