It would be nice if you could add more shapes to the no-go-zone selections (besides square/straight lines). Especially during Christmas, a circle around the tree would be good;)
Of course, variations might be nice as well like half circle or maybe triangle.
Another suggestion regarding no-go-zones is the placement of the zone. My fat fingers make it difficult to do any kind of fine adjustment and it can be difficult to see it while moving. Perhaps some buttons arrows on the sides to make incremental adjustments.