White pixel line around shapes
Ever since Appearance was introduced, my artwork on screen suffers from a white pixel line around shapes. Seems a rendering problem: the line is not actually existing - zooming in does not make it thicker, it's always one pixel. Tried switching GPU off and on. No difference.
The appearance of the black shape: Fill is black, Stroke is None.
Jan Vork commented
Update: the artefact only exists in CMYK mode, when black (K) is involved. Adding the adjacent color to the black makes the white edge disappear* (but setting the black shape to Overprint Fill doesn't...). Feels like the solution you need when designing for offset printing, to make sure colors register nice, whitout white gaps.
Seems like Illustrator is not equipped to handle anti-aliasing between CMYK colors correctly.
*) e.g. a black circle (CMYK 0/0/0/100) on a cyan background (100/0/0/0) shows the white edge. But a black+cyan circle (100/0/0/100) on a cyan background doesn't show it.