My fix was the same as the accepted solution but I had to specifically change my compatibility settings with "change settings for all users" option on Windows 10 which needs admin rights. I don't think I changed anything else. For reference, I am on a Aspire 7 laptop with 1920:1080 resolution.
Note: My WWconfig file works with any resolution but it seems that the game still reverts to 800:600 (and it it shown like that in the in-game config) with black bars. The picture is nicer because of my system resolution but it didn't really change the aspect ratio or anything when I put it on 1920:1080.
