Hello!
The following solution could fix your problem but I can't guarantee anything. Now don't worry! It's not because I have no idea what I'm telling you but the game is quite glitchy...so it might work for you without any further issues (or not).

Go to your game folder and look for the "game.ini" file. Open it with an editor and change the following line (it's the second line from the top):
Bildmodus=FULLSCREEN
to
Bildmodus=DIRECTWINDOW

Then save the file and start the game. You should now have the game in windowed mode and should be able to drag it to your preferred screen. I know this is not exactly what you asked for but I'm not aware of any other way to do something similar.