How to reproduce:
1. Create a new project and open it
2. Have a folder with 10-20 assets ready on the same monitor as the Editor
3. Drag and drop the assets to the Editor
4. Observe that the folder is non-responsive while assets are being imported and blocks the view to the Editor
5. Try to focus the Editor to see the progress bar

Expected result: the Editor is focusable while assets are being imported / new progress bar is shown. When trying to focus the Editor the progress bar is focused to the front
Actual result: the Editor is not focusable while the progress bar is shown. Trying to focus the Editor does nothing until the progress bar is cleared

Reproduced in: 2020.2.0a7, 2020.1.0b5, 2020.1.0a23
Not reproducible in: 2020.1.0a22, 2019.3.9f1, 2018.4.21f1