InvalidOperationException: Children collection already observed.
StackTrace:
   在 PropertyTools.Wpf.TreeListBox.InsertItem(Int32 index, Object item, Object parent)
   在 PropertyTools.Wpf.TreeListBox.InsertItems(Object parent, IList newItems, Int32 newStartingIndex)
   在 PropertyTools.Wpf.TreeListBox.Expand(Object item)
   在 System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   在 System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   在 System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   在 System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
   在 System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
   在 System.Windows.Data.BindingOperations.SetBinding(DependencyObject target, DependencyProperty dp, BindingBase binding)
   在 PropertyTools.Wpf.TreeListBox.PrepareContainerForItemOverride(DependencyObject element, Object item)
   在 System.Windows.Controls.ItemsControl.MS.Internal.Controls.IGeneratorHost.PrepareItemContainer(DependencyObject container, Object item)
   在 System.Windows.Controls.VirtualizingStackPanel.InsertContainer(Int32 childIndex, UIElement container, Boolean isRecycled)
   在 System.Windows.Controls.VirtualizingStackPanel.AddContainerFromGenerator(Int32 childIndex, UIElement child, Boolean newlyRealized, Boolean isBeforeViewport)
   在 System.Windows.Controls.VirtualizingStackPanel.MeasureChild(IItemContainerGenerator& generator, IContainItemStorage& itemStorageProvider, IContainItemStorage& parentItemStorageProvider, Object& parentItem, Boolean& hasUniformOrAverageContainerSizeBeenSet, Double& computedUniformOrAverageContainerSize, Double& computedUniformOrAverageContainerPixelSize, Boolean& computedAreContainersUniformlySized, Boolean& hasAnyContainerSpanChanged, IList& items, Object& item, IList& children, Int32& childIndex, Boolean& visualOrderChanged, Boolean& isHorizontal, Size& childConstraint, Rect& viewport, VirtualizationCacheLength& cacheSize, VirtualizationCacheLengthUnit& cacheUnit, Int64& scrollGeneration, Boolean& foundFirstItemInViewport, Double& firstItemInViewportOffset, Size& stackPixelSize, Size& stackPixelSizeInViewport, Size& stackPixelSizeInCacheBeforeViewport, Size& stackPixelSizeInCacheAfterViewport, Size& stackLogicalSize, Size& stackLogicalSizeInViewport, Size& stackLogicalSizeInCacheBeforeViewport, Size& stackLogicalSizeInCacheAfterViewport, Boolean& mustDisableVirtualization, Boolean isBeforeFirstItem, Boolean isAfterFirstItem, Boolean isAfterLastItem, Boolean skipActualMeasure, Boolean skipGeneration, Boolean isAncestorLookingForFirstItem, Boolean& hasBringIntoViewContainerBeenMeasured, Boolean& hasVirtualizingChildren)
   在 System.Windows.Controls.VirtualizingStackPanel.MeasureOverrideImpl(Size constraint, Nullable`1& lastPageSafeOffset, List`1& previouslyMeasuredOffsets, Nullable`1& lastPagePixelSize, Boolean remeasure)
   在 System.Windows.Controls.VirtualizingStackPanel.MeasureOverride(Size constraint)
   在 System.Windows.FrameworkElement.MeasureCore(Size availableSize)
   在 System.Windows.UIElement.Measure(Size availableSize)
   在 System.Windows.ContextLayoutManager.UpdateLayout()
   在 System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)
   在 System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
   在 System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
   在 System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
   在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)

InvalidOperationException: Children collection already observed.
StackTrace:
   在 BetterClip.Data.DataServiceBase`2.Save(IEnumerable`1 items)
   在 IntelliTools.Domain.Favorite.FavorItemExtension.MoveTo(IEnumerable`1 items, FavorItem parentItem, Int32 index)
   在 GongSolutions.Wpf.DragDrop.DragDrop.DropTargetOnDrop(Object sender, DragEventArgs e, EventType eventType)
   在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   在 System.Windows.OleDropTarget.RaiseDragEvent(RoutedEvent dragEvent, Int32 dragDropKeyStates, Int32& effects, DependencyObject target, Point targetPoint)
   在 System.Windows.OleDropTarget.MS.Win32.UnsafeNativeMethods.IOleDropTarget.OleDrop(Object data, Int32 dragDropKeyStates, Int64 point, Int32& effects)
   在 MS.Win32.UnsafeNativeMethods.DoDragDrop(IDataObject dataObject, IOleDropSource dropSource, Int32 allowedEffects, Int32[] finalEffect)
   在 System.Windows.OleServicesContext.OleDoDragDrop(IDataObject dataObject, IOleDropSource dropSource, Int32 allowedEffects, Int32[] finalEffect)
   在 System.Windows.DragDrop.OleDoDragDrop(DependencyObject dragSource, DataObject dataObject, DragDropEffects allowedEffects)
   在 System.Windows.DragDrop.DoDragDrop(DependencyObject dragSource, Object data, DragDropEffects allowedEffects)
   在 GongSolutions.Wpf.DragDrop.DragDrop.DoDragSourceMove(Object sender, Func`2 getPosition)
   在 GongSolutions.Wpf.DragDrop.DragDrop.DragSourceOnMouseMove(Object sender, MouseEventArgs e)
   在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   在 System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   在 System.Windows.Input.InputManager.ProcessStagingArea()
   在 System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
   在 System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   在 System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   在 System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   在 System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   在 MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   在 MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)