Comment 6 for bug 166252

I understand. However, why is AA using transparency all the
time? I would instead implement AA to merge the color of
the object with the one beside it. If beside the object
there is nothing, then merge color with transparency. But
if there is an object beside, merge both colors together.
So object A is 100% black, object B is 90% black, the pixel
on the boundary would be 95% black. That would look very
nice without any gap.

I assume that AA as implemented uses transparency because
this makes the implementation simple (you work on each
object individually without taking care of the objects
surrounding it). But you should check if it is easy to
change the AA algorithm to take into account objects that
share the same border.