In order for an object to appear "anti-aliased" as in smooth, you have to leave a 1px transparent border around the object, just like Crop does.
However that also expands Bounding-Box-based collision polygons to fit the new sprite body. Then gaps start to appear between objects.
Could we get a new option in the Collision Polygon setting in the Image/Sprite Editor that would enable to to scale the Collision Polygon? Like 99% of original value, or -1px smaller on all sides.
Manually setting the bounding box of a large square or triangle and making it absolutely perfect and even is a hell of a pain.