Strange things happen to my UI whenever I get an achievement for the first time...some text gets drop-shadowed and dialogs get doubled, and cooldown indicators turn opaque white. I don't have it in the screenshot, but healthbars seem to turn white as well.
It's fine after I quit and restart the game, so it's not AMG THE WORLD EXPLODE important, but it is odd.
I'm running on Mac OS X 10.10 via Steam. This seems to happen whether I'm running windowed or fullscreen.
