Rock County Board members will be sitting down Thursday night to consider a map of their own supervisory districts.  The board rejected a previous proposal when some members objected to finding themselves in the same district as other incumbents.  Board Chair Richard Bostwick contends the goal to avoid competition among incumbents is not like the state legislature’s partisan gerrymandering.  Bostwick says county board members aren’t choosing their own voters.  He says it’s more about retaining experience on the board and trust among constituents during difficult times.