anchor.diff:              let entity = get entityModel_ entityModelEntity
               let entityModelAddress = Test.GroupModelAddress @ [Lun.make entity.Name]
               refWorld := addEntityModel entityModelAddress entityModel_ world
  -            form.propertyGrid.SelectedObject <- { Address = entityModelAddress; RefWorld = refWorld }
  +            form.propertyGrid.SelectedObject <- { Address = entityModelAddress; WorldChangers = worldChangers; RefWorld = refWorld }
               !refWorld)
           refWorld := changer !refWorld
  -        gWorldChangers.Add changer)
  +        worldChangers.Add changer)
   
       form.deleteEntityButton.Click.Add (fun _ ->
           let selectedObject = form.propertyGrid.SelectedObject
  
positive.code: 
  type [<TypeDescriptionProvider (typeof<EntityModelTypeDescriptorProvider>)>] EntityModelTypeDescriptorSource =
      { Address : Address
        RefWorld : World ref }
  
  and EntityModelPropertyDescriptor (property : PropertyInfo) =
  
negative.code:             | Some entityModel ->
                  let entity = get entityModel entityModelEntity
                  let entityModelAddress = groupModelAddress @ [Lun.make entity.Name]
                  form.propertyGrid.SelectedObject <- { Address = entityModelAddress; WorldChangers = worldChangers; RefWorld = refWorld }
                  let entityModelTransform = getEntityModelTransform true (!refWorld).Camera entityModel
                  let mouseState = (!refWorld).MouseState
                  let dragState = DragPosition (entityModelTransform.Position + mouseState.MousePosition, mouseState.MousePosition, entityModelAddress)
  