This has been something small thats been bugging me for a while. When AA is turned on, the distracting pixelation in planets and fighter trails goes away, but objects sport christmas lights. I've seen this on XP with an nVidia card and on 7 with an ATI card.
Screenshot from Diplomacy below: top is without AA, bottom is with. Non-maskable, 2x, 4x, doesn't make much difference. It appears as though the AA is picking up white instead of transparent when doing calculations, reminding me of transparent gif errors.

I don't know how the code is written, but if it's a simple change like setting the default backdrop or expanding the textures a pixel or two, please try to sneak it in!