How to reproduce:
1. Open the attached "case_1191897-FullscreenTest(edit).zip" project
2. Load "SampleScene"
3. Go to Build Settings and click on "Add Open Scenes"
4. Build and Run the project on fullscreen mode
5. Open Windows Display settings and change resolution into a smaller one
6. Refocus on the build and notice how resolution changes are reflected
7. In Windows Display settings change back the resolution
8. Refocus on the build and observe the changes

Expected result: no black borders on the sides and Screen.currentResolution properly reflects the changes
Actual result: black borders on the sides and wrong Screen.currentResolution values

Reproduced with: 2018.3.0a2, 2018.4.12f1, 2019.2.10f1, 2019.3.0b8, 2020.1.0a9
Not reproduced with: 2017.4.33f1, 2018.2.0a1, 2018.3.0a1
Could not reproduce with: 2018.1.0f1, 2018.2.0b1, 2018.2.0f1 ("MethodAccessException" error on Build)

Notes:
- happens only in the Fullscreen Mode of the build
- happens on both display resolution change and display orientation change
- when the resolution is changed into a lower one, black borders appear and restrict mouse movement, however, currentResolution is properly reflected
- since resolution settings are saved globally, they can be manually changed if necessary through Registry Editor (Computer\HKEY_CURRENT_USER\Software\DefaultCompany\FullscreenTest)