Hi,

I have a very basic example where I bind a data grid to an
IList<Country> Nations {get; set;} property.

The Country class has two collections as properties:
IList<City> Cities { get; set;}
IList<Town> Towns { get; set;}.

I naturally get a nested grid of
Country1
+Cities
+Towns
Country2
+Cities
+Towns

When I drag a collapsed Cities, or Towns row, I immediately get a null reference exception:

System.IndexOutOfRangeException:Index was outside the bounds of the array.
   
Stack Trace:

   at Infragistics.Windows.DataPresenter.DataPresenterBase.RecordSelectionEnumerator.GetNextSiblingRecord(Int32 levelIndex, Boolean& retry)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.RecordSelectionEnumerator.GetNextSiblingRecord(Int32 levelIndex, Boolean& retry)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.RecordSelectionEnumerator.GetNextSiblingRecord(Int32 levelIndex, Boolean& retry)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.RecordSelectionEnumerator.MoveNext()
   at Infragistics.Windows.DataPresenter.DataPresenterBase.GetRecordsForSelection(Boolean select, RangeSelectionEvaluator evaluator)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.CalculateSelectionRange(Record record, SelectedItemHolder newSelection, Boolean clearExistingSelection, Boolean select)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.CalculateNewSelectionRange(ISelectableItem item, Boolean clearExistingSelection, Boolean select)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.InternalSelectRange(ISelectableItem item, Boolean clearExistingSelection, Boolean select)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.Infragistics.Windows.Selection.ISelectionHost.SelectRange(ISelectableItem item, Boolean clearExistingSelection)
   at Infragistics.Windows.Selection.SelectionStrategyExtended.OnMouseMove(ISelectableItem item, MouseEventArgs e)
   at Infragistics.Windows.Selection.SelectionController.OnMouseMove(MouseEventArgs e)
   at Infragistics.Windows.Controls.IGControlBase.OnMouseMove(MouseEventArgs e)
   at Infragistics.Windows.DataPresenter.DataPresenterBase.OnMouseMove(MouseEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
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