How to reproduce:
1. Open any project
2. Pop out a window like Project Browser so that it is not connected to anything
3. Resize it outwards
Expected result: Window resizes in real time
Actual result: Window resizes but newly created area is black until release of mouse button
Reproducible with: 2023.1.0b1, 2023.1.0b4
Not reproducible with: 2020.3.45f1, 2021.3.19f1, 2022.2.7f1, 2023.1.0a26
Reproduced on: Windows 11, RTX 3080ti