anchor.diff:                  ignore ^ MessageBox.Show ("Asset reload error due to: " + error + "'.", "Asset reload error", MessageBoxButtons.OK, MessageBoxIcon.Error)
                   world
   
  +    let private handleFormGroupTabDeselected (form : GaiaForm) (_ : EventArgs) =
  +        addWorldChanger ^ fun world ->
  +            let world = unsubscribeFromEntityEvents world
  +            deselectEntity form world
  +            refreshPropertyGrid form world
  +            refreshTreeView form world
  +            world
  +
       let private handleFormGroupTabSelected (form : GaiaForm) (_ : EventArgs) =
           addWorldChanger ^ fun world ->
  -            let world = unsubscribeFromEntityEvents world
               let world =
                   World.updateUserState (fun editorState ->
                       let groupTabs = form.groupTabs
  
positive.code:             if World.containsEntity entityTds.DescribedEntity world
              then form.propertyGrid.Refresh ()
              else deselectEntity form world
          | _ -> deselectEntity form world
  
      let private refreshTreeView (form : GaiaForm) world =
          let treeState = getExpansionState form.treeView
  
negative.code:                     { editorState with SelectedGroup = stog Simulants.EditorScreen !!groupTab.Text })
                      world
              let world = subscribeToEntityEvents form world
              refreshPropertyGrid form world
              refreshTreeView form world
              world
  