> Strangely enough, when I crop a larger image, the resized image appears 100% correct. Then I save it, open it again, and then it gets displayed with the borders again.
Well, that sounds like a display problem (i.e. the border is not part of the image).
My guess is that this will disappear once you set the window position to Centered.
Alternatively, you could pick a different background color for view windows (Options | Viewing | Tab:Appearance | Background Colors). I'm using a soft, beige-like color myself. It looks fairly neutral, but is still easily recognizable as 'background' because any borders that my images have are usually either white or black.