ランキング参加中プログラミング ObservableGroup<TKey, TElement> and ReadOnlyObservableGroup<TKey, TElement> Sample ObservableGroup<TKey, TElement> features ObservableGroupedCollection<TKey, TElement> and ReadOnlyObservableGroupedCollection<TKey, TElement> ObservableGroupedCollection<TKey, TElement> features 参考 Obse…