-Sometimes dropdown closes and properties stay outside the dropdown.
-Sometime dropdown opens and no properties get a display.
-Gizmo properties do not refresh on closing /opening dropdown in physics 2D under the Project Settings window.
-On moving mouse cursor it gets refreshed.

Steps to repro:
1. Create a new project
2. Edit Project Settings > Physics 2D.
3. Gizmos > Click on Dropdown arrow(Don't move the cursor).
4. Repeat steps 3, for 2-3 time.

Actual Result:
Gizmo properties do not refresh on closing /opening dropdown

Expected Result:
Gizmo properties should refresh on closing /opening dropdown

Reproducible in:
2020.1.0b16, 2020.1.0a1, 2019.4.3f1, 2019.3.15f1, 2019.3.0a1, 2019.2.1f1, 2019.1.0f1, 2018.4.25f1, 2018.3.0a1.

Working Fine in:
2020.2.0a18, 2018.2.0f2.

Environment:
Occurring on Windows 10 & Mac 10.15.