Add "Check Disable Visual Themes" and your problem should be gone.
Did not fix it :(
I found somewhat a playable remedy... using the new target command "'-nofixaspect" + "-w" (To go full windowed mode) it doesnt have the problem.
Now the problem with that is the graphics suffer as it uses the brightness options of ur desktop and it doesnt look as good as if it were normal fullscreen.
Any Blizz Reps out there that know how to fix this :(