anchor.diff:                   Content.entities field (fun field _ -> field.Props) (fun props _ -> props) $ fun _ prop _ ->
                       Content.entity<PropDispatcher> Gen.name
                           [Entity.Prop <== prop
  -                         Entity.Prop.ChangeEvent ==|> fun evt -> let prop = evt.Data.Value :?> Prop in msg (UpdatePropState (prop.PropId, prop))]
  +                         Entity.Prop.ChangeEvent ==|> fun evt -> msg (UpdatePropState (evt.Data.Value :?> Prop))]
   
                    // spirit orb
                    Content.entityIf field (fun field _ -> Field.hasEncounters field) $ fun field _ ->
  
positive.code:                 // no transition
                  | None -> just field
  
              | UpdatePropState (propId, prop) ->
                  let field = Field.updateProp (constant prop) propId field
                  just field
  
              | MenuTeamOpen ->
  
negative.code:         | Update
          | UpdateAvatar of Avatar
          | UpdateFieldTransition
          | UpdatePropState of Prop
          | MenuTeamOpen
          | MenuTeamAlly of int
          | MenuItemOpen
  