Works for me, but with some oddities. Playing on Windows 10.

- Confirmed that a fresh install Jazz2Plus folder lfrom GOG acks directdraw fullscreen as mentioned in this forum post

- Subsequent launches works as described above. Small note that GOG installs with HIGHDPIAWARE registry already in there and this new plus.dll gives it a second time, without checking if it's already present. So it ends up with the line "DWM8And16BitMitigation HIGHDPIAWARE HIGHDPIAWARE".

-Renaming the folder into different folders, or making a new folder and copying all files into it interestingly enough does never make directdraw dissapear. When launching and refreshing the registry DW8And16Bitmitigation is added to the new folder and it works immediately on the FIRST launch and subsequent launches.

-Thus the only way of removing directdraw (for one launch) I could find is if I remove the registry manually.