IIRC, the way Ficedula got FF7 to run in windowed mode was editing ff7.exe in Assembly. There's a boolean statement that says something to the effect of:
windowed mode = FALSE
which just had to be switched. It wasn't exactly like that, but you get the idea. If anyone knows Assembly (I don't), give it a try!
Obligatory reminder, in homage to Dagsverre: never change the length of an .exe file.