void RegisterFilterItem(OfficeNavigationBar navigationBar, FilterItemBase item)
        {
            NavigationBarItem navItem = new NavigationBarItem();

            navItem.Tag  = item;
            navItem.Text = ViewModel.GetFilterName(ViewModel.StaticFilters, item);
            navItem.Name = "filterItem" + item.Name.Replace(" ", string.Empty);
            navigationBar.Items.Add(navItem);
            navItem.BindCommand((f) => ViewModel.Select(f), ViewModel, () => (item as FilterTreeViewModel <TEntity, TID, TUnitOfWork> .FilterItem));
        }
 protected override void BindAllFoldersItem(NavigationBarItem allFoldersItem)
 {
     allFoldersItem.BindCommand(() => CollectionViewModel.ShowAllFolders(), CollectionViewModel);
 }