Oh yes I see your point, it's true it's a bit annoying. Well, in fact I center the "runtime" screen because I control it completly (directx, textures, polygons, etc
). The GUI is old obscur win32 gdi stuff. I suppose it's easy to do, maybe I have to check this in the next release.
By the way did you try the GPU mode? it should enlarge the screen to your native laptop resolution, should be cool to watch demos in fullscreen