Not sure how much of a "bug" this is, but the Mac app is a little wonky. I'd recommend disabling resizing the window-- it screws up the pixels in a major way, and I think it's also responsible for the ugly border along the right side and bottom. Also, just as a side question, how is full screen meant to look?
I've just started playing, so its all familiar from the beta so far, but I'm so incredibly exited!