Reproduction steps:
1. Create a new project
2. Drag inner windows around the display
3. Observe the window preview behaviour
Expected results: The docking preview window maintains proper size, is confined within the editor boundaries, unless the intent is for it to become a separate window, always has the default background color, without flickering
Actual results: The doking preview window gets enlarged when dragging around the editor, extends to other displays, and sometimes flickers from gray to black
Reproduced with: 2021.3.49f1, 2022.3.61f1, 6000.0.46f1, 6000.1.0b14, 6000.2.0a8
Reproduced on: Ubuntu 24.04
Not reproduced on: Windows 11
Note: Reproduction videos are attached in the comments