This is more out of curiosity than anything else, but when I press Alt+Z to remove the UI, the bottom of the screen is covered by a blackened area. The area somewhat fits the actionbars, so I'm guessing it's related to that.
Has the field of view been stretched so that the bottom part of the UI doesn't interfere with the view?
1280x1024 and using the 1.25 aspect ratio.
Example.