System Information
Operating system: Linux-4.15.0-20-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: Mesa DRI Intel(R) Haswell Mobile Intel Open Source Technology Center 4.5 (Core Profile) Mesa 18.0.5

Blender Version
Broken: version: 2.81 (sub 10), branch: master, commit date: 2019-09-10 22:12, hash: rB4ce3fbd52ae8
Worked: (optional)

Short description of error
Someone has changed the system's behaviour on this aspect. If you're now in 'Preferences' and wanted to perform 'Exports' then the 'Export' windows takes over the one for 'Preferences', as shown in this video

where this is not the case in the release 2.80:

As a translator and a user, I personally would prefer the behaviour in release 2.80 than the current one. Please put it back to where it was.