public void Insert(int index, T item)
{
items.Insert(index, item);
CollectionChanged.Raise(this, NotifyCollectionChangedEventArgs.Add(item, index));
PropertyChanged.Raise(this, CountPropertyChangedEventArgs);
}
public void Add(T item)
{
items.Add(item);
CollectionChanged.Raise(this, NotifyCollectionChangedEventArgs.Add(item, Count - 1));
PropertyChanged.Raise(this, CountPropertyChangedEventArgs);
}