OneAlex has a d3d dll and ini file in the root of the game folder, and that is how SH3 with OneAlex determines the resolution it will run at. I would put main.cfg back the way it was. You could read up on editing the d3d.ini file, and maybe get windowing done there, but a 1920 game "windowed" on a 3440 screen is going to be a bit difficult to see, unless you have really really good, young eyes...
What are you trying to do with a "windowed" game? If you think it will "shell-out" easier, it will, but it still causes issues with the game.
