The Snap! stage is a view of an infinite plane. Sprites can be anywhere on the plane. In berkeley logo, the screen is a torus, and if the turtle is partly off screen, then it is on the other side of the screen. I suggest that that feature be added to Snap! because I always use it with wrap mode on, and Snap! does not have it.
I recommend moving this to "Feature requests" so more people will see it