How to reproduce:
1. Start one of the "Basic Tutorials" levels
2. Open the Preferences window
3. Try to close the Preferences window

Expected result: Preferences window closes
Actual result: Preferences window does not close

Reproducible with - 2018.3.0a4, 2018.3.3f1
Not reproducible with - 2017.4.19f1, 2018.3.0a3
Could not test with - 2019.1, 2019.2

Workaround: User must restart the tutorial

Notes:
2017.4 and early versions of the 2018.3 used the different UI for the Preferences window and it could be closed during the tutorial (Snapshot_1117370_V1)
On both 2017.4 and 2018.3 versions, Editor windows (E.g. Tile Palette or Animation) become locked when opened during the tutorial
Tutorial levels do not work properly with any of the 2019.1 or 2019.2 versions