anchor.diff:  end;
   
   procedure TMainForm.btnAddClicked(Sender: TObject);
  -begin
  -
  +var
  +  lData: TPerson;
  +begin
  +  lData := TPerson.CreateNew;
  +  lData.Name := 'New Name';
  +  lData.Age := 12;
  +  FList.Add(lData);
   end;
   
   procedure TMainForm.btnEditClicked(Sender: TObject);
   begin
  +  if medGrid.SelectedObject = nil then
  +    Exit;
     EditPerson(TPerson(medGrid.SelectedObject));
   end;
   
   procedure TMainForm.btnDeleteClicked(Sender: TObject);
   begin
  -
  +  medGrid.SelectedObject.Deleted := True;
  +  FList.NotifyObservers;
   end;
   
   procedure TMainForm.btnUpdateClicked(Sender: TObject);
  
positive.code:     ImageName := '';
      TabOrder := 7;
      OnClick := @btnAddClicked;
      Enabled := False;
    end;
  
    btnEdit := TfpgButton.Create(self);
  
negative.code:   lData: TPerson;
  begin
    lData := medGrid.SelectedObject as TPerson;
    if lData = nil then
      Exit;
    edtName.Text  := lData.Name;
    edtAge.Text   := IntToStr(lData.Age);
  end;
  