anchor.diff:              let isNew = not ^ World.containsEntity entity world
               if isNew || mayReplace then
   
  -                // get old world for entity tree rebuild
  +                // get old world for entity tree rebuild and change events
                   let oldWorld = world
                   
                   // adding entity to world
  
positive.code:             let oldWorld = world
              let world = World.updateScreenStateWithoutEvent updater screen world
              World.publishScreenChange propertyName screen oldWorld world
  
          /// Query that the world contains the proxied screen.
          static member containsScreen screen world =
  
negative.code:             let transmutedEntity = group.GroupAddress -<<- ntoa<Entity> name |> Entity.proxy
              let world = World.addEntity false entityState transmutedEntity world
              (transmutedEntity, world)
  
          /// Try to set an entity's optional overlay name.
          static member trySetEntityOptOverlayName optOverlayName entity world =
  