AcManager.Pages.Dialogs.SelectTrackDialog.Tabs_OnNavigated C# (CSharp) Метод

        private void Tabs_OnNavigated(object sender, NavigationEventArgs e) {
            if (_list != null) {
                _list.PropertyChanged -= List_PropertyChanged;
            }

            if (_choosing != null) {
                _choosing.ItemChosen -= Choosing_ItemChosen;
            }

            var content = ((ModernTab)sender).Frame.Content;
            _list = content as ISelectedItemPage<AcObjectNew>;
            _choosing = content as IChoosingItemControl<AcObjectNew>;

            if (_list != null) {
                _list.SelectedItem = Model.SelectedTrackConfiguration?.MainTrackObject;
                _list.PropertyChanged += List_PropertyChanged;
            }

            if (_choosing != null) {
                _choosing.ItemChosen += Choosing_ItemChosen;
            }
        }