Wrong ObservableCollection EventArg after drag/drop

[tonecool]

I'm using ObservableCollection which is bound to ItemsControl ItemsSource property.

What I expect to get after drag and drop an item within control is NotifyCollectionChangedAction.Move event like this:

        private void MyCollection_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            if (e.Action == NotifyCollectionChangedAction.Move)
            {
                //DO something
            }
        }

But instead I'm getting two events (NotifyCollectionChangedAction.Remove and NotifyCollectionChangedAction.Add). I'm not sure if this is by design but in my case it was complicating the logic to decide if there was new item added externally or just drag/dropped existing control item.

Repo

I can provide code example if needed.

Environment

• GongSolutions.WPF.DragDrop 2.2.0
• Windows 10
• Visual Studio 2019
• .NET Framework 4.7.2

[punker76]

@tonecool I think that's because the default drop handler uses the RemoveAt and Insert methods of the source and destination. If you know that's always the same then you can implement your own drop handler which then uses the move method. If you find a solution then you can try to add this here and make a PR. Thx 🙏

[Mogikan]

Use case when it's important: you need to implement Undo/Redo. Because when you undo it deletes an item, but does not paste it back.