private async void addToolbarItem_Click(object sender, EventArgs e)
        {
            var editViewModel = new AvailableEntryEditViewModel(null);
            var page          = new AvailableEntryEditPage();

            page.BindingContext = editViewModel;
            await((MainPage)App.Current.MainPage).NavigateTo(page, true);
        }
        protected async void Edit_Clicked(object sender, EventArgs e)
        {
            var entry         = (sender as MenuItem).CommandParameter as DataLayer.Models.Entry;
            var editViewModel = new AvailableEntryEditViewModel(entry);
            var page          = new AvailableEntryEditPage();

            page.BindingContext = editViewModel;
            await((MainPage)App.Current.MainPage).NavigateTo(page, true);
        }
        protected async void Handle_ItemTapped(object sender, EventArgs e)
        {
            var args = e as ItemTappedEventArgs;

            if (args.Item == null)
            {
                return;
            }

            var entry         = (args.Item as DisplayItem).Tag as DataLayer.Models.Entry;
            var editViewModel = new AvailableEntryEditViewModel(entry);
            var page          = new AvailableEntryEditPage();

            page.BindingContext = editViewModel;
            await((MainPage)App.Current.MainPage).NavigateTo(page, true);
        }