letterbox mode for ingame client

Right now I have a 1920x1200 screen. I have a choice of a) run in a 1920x1080 window (which is buggy) b) run fullscreen 1920x1200.. which observant people know actually gives me LESS VISION OF THE RIFT c) run fullscreen 1920x1080... which distorts things.

It would be really nice to have a fullscreen-letterbox mode, rather than the stretch-to-fit default. Please add.