Cannot modify the logical children for this node at this time because a tree walk is in progress

[Simon]

Hi,

I am using version 2014.1.0310.40

I create a map with 3 layers, all of which inherit from VisualizationLayer.  Sometimes when I delete one of these layers, I get the following exception

Cannot modify the logical children for this node at this time because a tree walk is in progress.  
at System.Windows.FrameworkElement.RemoveLogicalChild(Object child)
   at System.Windows.Controls.UIElementCollection.RemoveInternal(UIElement element)
   at System.Windows.Controls.UIElementCollection.Remove(UIElement element)
   at Telerik.Windows.Controls.Map.MapLayerCell.RemoveItem(MapObjectInfo info)
   at Telerik.Windows.Controls.Map.VisualizationLayer.AddItemToCluster(MapObjectInfo newInfo)
   at Telerik.Windows.Controls.Map.VisualizationLayer.AddItemToClusterOrCell(MapObjectInfo info)
   at Telerik.Windows.Controls.Map.VisualizationLayer.ArrangeItem(Object item)
   at Telerik.Windows.Controls.Map.MapLayer.LocationChangedHandler(DependencyObject source, DependencyPropertyChangedEventArgs eventArgs)
   at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp, Boolean preserveCurrentValue)
   at System.Windows.StyleHelper.InvalidateContainerDependents(DependencyObject container, FrugalStructList`1& exclusionContainerDependents, FrugalStructList`1& oldContainerDependents, FrugalStructList`1& newContainerDependents)
   at System.Windows.StyleHelper.DoStyleInvalidations(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle)
   at System.Windows.StyleHelper.UpdateStyleCache(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle, Style& styleCache)
   at System.Windows.FrameworkElement.OnStyleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
   at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp, Boolean preserveCurrentValue)
   at System.Windows.FrameworkElement.UpdateStyleProperty()
   at System.Windows.FrameworkElement.InvalidateTreeDependentProperties(TreeChangeInfo parentTreeState, Boolean isSelfInheritanceParent)
   at System.Windows.FrameworkElement.OnAncestorChangedInternal(TreeChangeInfo parentTreeState)
   at System.Windows.TreeWalkHelper.OnAncestorChanged(DependencyObject d, TreeChangeInfo info, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at MS.Internal.PrePostDescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren)
   at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren)
   at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d)
   at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at MS.Internal.PrePostDescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren)
   at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren)
   at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d)
   at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at MS.Internal.PrePostDescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren)
   at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren)
   at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d)
   at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at MS.Internal.PrePostDescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren)
   at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren)
   at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d)
   at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at MS.Internal.PrePostDescendentsWalker`1._VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d, Boolean visitedViaVisualTree)
   at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren)
   at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d)
   at System.Windows.DescendentsWalker`1.StartWalk(DependencyObject startNode, Boolean skipStartNode)
   at MS.Internal.PrePostDescendentsWalker`1.StartWalk(DependencyObject startNode, Boolean skipStartNode)
   at System.Windows.TreeWalkHelper.InvalidateOnTreeChange(FrameworkElement fe, FrameworkContentElement fce, DependencyObject parent, Boolean isAddOperation)
   at System.Windows.FrameworkElement.OnVisualParentChanged(DependencyObject oldParent)
   at System.Windows.Media.Visual.FireOnVisualParentChanged(DependencyObject oldParent)
   at System.Windows.Media.Visual.RemoveVisualChild(Visual child)
   at System.Windows.Media.VisualCollection.DisconnectChild(Int32 index)
   at System.Windows.Media.VisualCollection.RemoveRange(Int32 index, Int32 count)
   at System.Windows.Controls.UIElementCollection.RemoveRangeInternal(Int32 index, Int32 count)
   at System.Windows.Controls.Panel.RemoveChildren(GeneratorPosition pos, Int32 containerCount)
   at System.Windows.Controls.Panel.OnItemsChangedInternal(Object sender, ItemsChangedEventArgs args)
   at System.Windows.Controls.Panel.OnItemsChanged(Object sender, ItemsChangedEventArgs args)
   at System.Windows.Controls.ItemContainerGenerator.OnItemRemoved(Object item, Int32 itemIndex)
   at System.Windows.Controls.ItemContainerGenerator.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Windows.WeakEventManager.ListenerList`1.DeliverEvent(Object sender, EventArgs e, Type managerType)
   at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args)
   at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.Windows.Controls.ItemCollection.OnViewCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.WeakEventManager.ListenerList`1.DeliverEvent(Object sender, EventArgs e, Type managerType)
   at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args)
   at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.Windows.Data.ListCollectionView.ProcessCollectionChangedWithAdjustedIndex(NotifyCollectionChangedEventArgs args, Int32 adjustedOldIndex, Int32 adjustedNewIndex)
   at System.Windows.Data.ListCollectionView.ProcessCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.Windows.Data.CollectionView.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.RemoveItem(Int32 index)
   at System.Collections.ObjectModel.Collection`1.Remove(T item)
   at Apteco.Client.Visualisations.Map.WPF.Map.Model.Layers.LayersCollection.RemoveLayer(String layerName)

At present I have caught the exception and carried on, but I would be interested in fixing the issue

Thanks
Simon

[Petar Mladenov]

Hi Simon,

I think there is no much information about this System Exception in the net so we will need to reproduce it locally for better investigation. We tried in a sample project which you may find attached. There is a button which removes the first layer in the RadMap. Are you able to reproduce the issue in our project ? If not, is it possible for you to open a new support thread with an isolated project. If we found a solution , we will update this forum post too in order to help others who might also encounter this issue.
Thank you in advance for your cooperation.

Regards,
Petar Mladenov
Telerik