Operating system: Windows 10
Graphics card: Nvidia GeForce GTX 1070
Broken: version: 2.80 (sub 39), branch: master, commit date: 2018-12-22 09:56, hash: 4c5e76025d83, type: Release
Short description of error
When in fullscreen mode, the preferences window opens behind the main window (but still gets input focus).
Exact steps for others to reproduce the error
click "Toggle window fullscreen" in the "Window" menu to make the main window occupy the entire screen,
click "Preferences..." in the "Edit" menu.
Expected result: The preferences window should open in front of the main window and receive input focus.
Observed result: The preferences window opens behind the main window but receives input focus anyway, making parts of the main window temporarily unresponsive to mouse clicks. Alt-Tab (on Windows) reveals the preferences window.