Using non standard window sizes?

[valle2000]

If I resize a WoW-window to a non standard resolution like e.g. 1920x600 the ratio between height and length gets weird.
(Everyone looks short and fat).

Is there anyway I please can resize a window to a-kind-of letterbox widescreen and still get a correct visual proportion?

Edit: If I e.g. use eyefinity at resolution 3840x1200 I get correct proportions. Can I get the same result in some way by setting a window size of 1920x600?