How to reproduce:
1. Open the attached "Repro" project
2. Build and run it, make sure that the build is in a windowed mode and selected resolution is small
3. Wait for the game to load, Alt+Tab away from it
4. Press on its border or try to exit the game

Expected result: Build stays in its current position and you can close it
Actual result: Build is jumping downwards if you press on its border and can't be closed

Reproducible with - 2017.1.0a2, 5.6.0b10, 5.5.2p1, 5.4.4p2

Note: Reproducible on Windows 7 or Windows 10. Can't reproduce the issue on macOS 10.12.3

Fixed in 2017.2.0a4