In the Inspector window, when the Dropdown window opens with the left mouse click button, then it does not get closed with the same left mouse click button. It closes with the right mouse click button.

Steps to repro:
1. Create a new project
2. Hierarchy > 3D Object > Cube > Inspector > Mesh Renderer > Light Probs
3. Open dropdown window with left click and close it with same lift click
4. Observe dropdown window does not get closed with left click.
Note: The issue is occurring for all the dropdown buttons.

Actual Result:
A Dropdown window does not get open and close with the same mouse click button.

Expected Result:
A Dropdown window gets close with the left mouse click button.

Occurring in:
2020.2.0a20, 2020.2.0a19

Working fine in:
2020.2.0a18, 2020.1.0f1, 2019.4.6f1

Environment:
Windows10