anchor.diff:              let world = updateEditorState (fun editorState -> { editorState with DragCameraState = DragCameraNone }) world
               (Resolve, world)
           | DragCameraNone -> (Resolve, world)
  +
  +    let private monitorGroupEvents form world =
  +        let world = World.monitor (handleNuGroupRegister form) (Events.Register --> Globals.Screen --> Events.Wildcard) Globals.Screen world
  +        let world = World.monitor (handleNuGroupUnregistering form) (Events.Unregistering --> Globals.Screen --> Events.Wildcard) Globals.Screen world
  +        world
   
       let private monitorEntityEvents (group : Group) form world =
           let world = World.monitor (handleNuChangeParentNodeOpt form) (Events.Change Property? ParentNodeOpt --> group --> Events.Wildcard) group world
  
positive.code:                     | Some _ -> (defaultGroup, world) // NOTE: conclude world is already attached
                  | [] -> failwith ("Cannot attach Gaia to a world with no groups inside the '" + scstring Globals.Screen + "' screen.")
              let world = List.fold (fun world group -> monitorEntityEvents group form world) world groups
              (defaultGroup, world)
          else failwith ("Cannot attach Gaia to a world with a screen selected other than '" + scstring Globals.Screen + "'.")
  
  
negative.code:         refreshOverlayComboBox form Globals.World
          refreshCreateComboBox form Globals.World
          refreshEntityTreeView form Globals.World
          refreshGroupTabs form Globals.World
          refreshHierarchyTreeView form Globals.World
          selectGroup defaultGroup form Globals.World
          form.tickingButton.CheckState <- CheckState.Unchecked
          form.songPlaybackButton.CheckState <- if World.getMasterSongVolume world = 0.0f then CheckState.Unchecked else CheckState.Checked
  