none [Windowed Mode] Screen Resolution Changes Impossible?

I've been trying to get the game window to be smaller than my max native resolution (2560x1440), and just cannot seem to get it to behave. I've disabled adjust to desktop resolution, I've edited both resolution entries in the relevant files, and yet it still launches locked to 2560x1440. Is there any workaround for this that doesn't involve rescaling the desktop, given how much of a hassle that is?