AD Mac: hairline around STROKE?

[VectorCat]

I'm showing two images because when the item is selected, it hides the hairline, but unless it is selected, you can't see my stroke / fill combo. This is something which doesn't appear only in Designer, which is bad enough, but also in exported EPS.

Is this a Bug? 

 

[prophet]

Is the stroke aligned to the "inside"?

[lepr]

It's not a bug; it is a consequence of rendering with antialiasing. 

The black filled spike object has a white inside-aligned stroke. An inside- or outside-aligned stroke is implemented as a separate object which provides the illusion of a stroke. (Expand Stroke command will give you that stroke-like object if you are unsure of what I mean.) The antialiasing of the outermost edge of the white stroke-like object is allowing partial visibility of the coinciding outermost edge of the black fill object that lies underneath the stroke-like object.

[VectorCat]

I do understand. Thank you both for the clarification!