Issue: The Sims 3 under Ubuntu Linux with PlayOnLinux or WINE will not run in fullscreen mode
An easy fix to this problem: (it must be done each time you start the game)
Open up your Options menu (The “…” icon), and go to Display Settings.
Uncheck the “Fullscreen” box, and apply the settings by clicking the checkbox.
At this point, you will see a box asking you if you want to keep the changes. Click nothing, just let it go by. It will revert the settings and go into proper fullscreen.
I have failed to find a peremenent solution, but this takes very little time to complete.
Thank you! You often write very interesting articles.