**System Information**
Operating system: Linux-5.8.16-300.fc33.x86_64-x86_64-with-fedora-33-Thirty_Three 64 Bits
Graphics card: Mesa DRI Intel(R) HD Graphics 4000 (IVB GT2) Intel Open Source Technology Center 4.2 (Core Profile) Mesa 20.2.1
**Blender Version**
Broken: version: 2.91.0 Beta, branch: master, commit date: 2020-10-30 16:36, hash: `rB8b806c86e12e`
Worked: (newest version of Blender that worked as expected)
**Short description of error**
Preferences window size changes to near full screen
**Exact steps for others to reproduce the error**
- Launch Blender, Load Factory Settings
- Open the Preferences under Edit-menu
- Leave the Preferences window open yet go to the main Blender window by clicking in its window.
- Start a render with F12, let it finish
- Press ESC to close the Blender render window
You will now find that the Preferences window has changed size to near full screen!