How to reproduce:
1. Create a new project
2. Click on the "Layers" tab in the top right corner of the Editor
3. While the context menu is still open move the Editor (Top Windows bar)
4. Observe that the "Layers" context menu is still open

Expected result: PopupWindow type context menus automatically close when moving the Editor Window
Actual result: PopupWindow type context menus stay open in a "frozen-like" state when moving the Editor Window

Reproduced in: 2021.2.0a3, 2021.1.0b4, 2020.2.3f1, 2020.1.17f1, 2020.1.0a22
Not reproducible in: 2020.1.0a21, 2019.4.19f1