protected override void OnDragDrop(ITreeViewItem item, IDataObject data) { SubCategory subCategory = item as SubCategory; if (subCategory.IsNullObj()) { return; } TransactionDropDownData transactionDropDownData = data.GetData(typeof(TransactionDropDownData)) as TransactionDropDownData; if (transactionDropDownData.IsNullObj()) { return; } EventTransactionDropped eventTransactionDropped = new EventTransactionDropped(); eventTransactionDropped.TransactionDropDownData = transactionDropDownData; _aggregator.PublishEvent <EventTransactionDropped>(eventTransactionDropped); }