ObservableCollection : calling OnCollectionChanged with multiple new items

please note that I am trying to use NotifyCollectionChangedAction.Add action instead of .Reset. the latter does work, but it is not very efficient with large collections.

so i subclassed ObservableCollection:

public class SuspendableObservableCollection<T> : ObservableCollection<T>

for some reason, this code:

private List<T> _cachedItems;
...

    public void FlushCache() {
        if (_cachedItems.Count > 0) {

        foreach (var item in _cachedItems)
            Items.Add(item);

        OnCollectionChanged(new NotifyCollectionChangedEventArgs(
            NotifyCollectionChangedAction.Add, (IList<T>)_cachedItems));
        }
    }

is throwing A collection Add event refers to item that does not belong to collection

this appears to be a bug in BCL ?

I can step through and see prior to calling OnCollectionChanged that new items are added to this.Items

WOW

just made a staggering discovery. None of these approaches worked for me (flush, addrange), because the error appears to be triggered ONLY if this collection is bound to my Listview!!

TestObservableCollection<Trade> testCollection = new TestObservableCollection<Trade>();
List<Trade> testTrades = new List<Trade>();

for (int i = 0; i < 200000; i++) 
    testTrades.Add(t);

testCollection.AddRange(testTrades); // no problems here.. 
_trades.AddRange(testTrades); // this one is bound to ListView .. BOOOM!!!

In conclusion, ObservableCollection does support adding incremental lists, but a ListView doesn't. Andyp figured out a workaround to make it work with CollectionView below, but since .Refresh() is called, that is no different than just calling OnCollectionChanged( .Reset )..