Gosh, I'd like to help as well. Have no idea though. I know Shogun: TW had a windowed-mode which is sort of widescreen such as in dvd movies but it just basically just blocks some areas with panels. If you only need a portion of the screen, why not just manually adjust the monitor to make the screen smaller? I assume the player has limited field of view or movement reason why you're trying to minimize the screen.

Maybe one of the Moderators can get this to the Apothecary or Mods section?