RadPanne.IsHidden=true NullReferenceException

[Daniel]

Hi,

following code throws an NullReferenceException on radPadne.IsHidden = true when closing app. (MainWindow.Closing event)

private void PaneSource_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
  if (e.NewItems != null)
  {
    foreach (var paneVM in e.NewItems.OfType<ILayoutPane>())
    {
      addRadPane(paneVM);
    }
  }
  if (e.OldItems != null)
  {
    foreach (var paneVM in e.OldItems.OfType<ILayoutPane>())
    {
      RadPane radPane = docking.FindRadPaneBySerializationId(paneVM.Id);
      if (radPane != null)
      {
        radPane.IsHidden = true; //This throws an exception
        radPane.DataContext = null;
      }
    }
  }
}

StackTrace:

at Telerik.Windows.Controls.Primitives.TabStripPanel.<>c__DisplayClass14.<MeasureOverride>b__7(UIElement item) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Navigation\TabControl\TabStripPanel.cs:line 176
at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
at System.Linq.Enumerable.Max(IEnumerable`1 source)
at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
at Telerik.Windows.Controls.Primitives.TabStripPanel.<>c__DisplayClass14.<MeasureOverride>b__6(Double total, List`1 next) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Navigation\TabControl\TabStripPanel.cs:line 174
at System.Linq.Enumerable.Aggregate[TSource,TAccumulate](IEnumerable`1 source, TAccumulate seed, Func`3 func)
at Telerik.Windows.Controls.Primitives.TabStripPanel.MeasureOverride(Size availableSize) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Navigation\TabControl\TabStripPanel.cs:line 171
at System.Windows.FrameworkElement.MeasureCore(Size availableSize)
at System.Windows.UIElement.Measure(Size availableSize)
at System.Windows.ContextLayoutManager.UpdateLayout()
at System.Windows.UIElement.UpdateLayout()
at Telerik.Windows.Controls.RadPane.OnDocumentHostTemplateChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Docking\Docking\Docking\RadPane.cs:line 1261
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.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.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 MS.Internal.Controls.InnerItemCollectionView._RemoveAt(Int32 index, Int32 indexR, Object item)
at MS.Internal.Controls.InnerItemCollectionView.Remove(Object item)
at System.Windows.Controls.ItemCollection.Remove(Object removeItem)
at Telerik.Windows.Controls.RadPaneGroup.CloseSinglePane(RadPane pane) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Docking\Docking\Docking\RadPaneGroup.cs:line 1331
at Telerik.Windows.Controls.RadPaneGroup.ClosePane(RadPane pane) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Docking\Docking\Docking\RadPaneGroup.cs:line 622
at Telerik.Windows.Controls.RadDocking.OnPaneClose(RadPane pane) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Docking\Docking\Docking\RadDocking.cs:line 874
at Telerik.Windows.Controls.RadDocking.OnRadPaneClose(Object sender, StateChangeCommandEventArgs args) in c:\TB\105\WPF_Scrum\Release_WPF\Sources\Development\Controls\Docking\Docking\Docking\RadDocking.cs:line 840

CallStack:

    Telerik.Windows.Controls.Navigation.dll!Telerik.Windows.Controls.Primitives.TabStripPanel.MeasureOverride.AnonymousMethod__7(System.Windows.UIElement item) Line 176 + 0x68 bytes   C#
    System.Core.dll!System.Linq.Enumerable.WhereSelectListIterator<System.Windows.UIElement,double>.MoveNext() + 0x69 bytes
    System.Core.dll!System.Linq.Enumerable.Max(System.Collections.Generic.IEnumerable<double> source) + 0x3c bytes
    System.Core.dll!System.Linq.Enumerable.Max<System.Windows.UIElement>(System.Collections.Generic.IEnumerable<System.Windows.UIElement> source, System.Func<System.Windows.UIElement,double> selector) + 0x38 bytes
    Telerik.Windows.Controls.Navigation.dll!Telerik.Windows.Controls.Primitives.TabStripPanel.MeasureOverride.AnonymousMethod__6(double total, System.Collections.Generic.List<System.Windows.UIElement> next) Line 174 + 0x34 bytes    C#
    System.Core.dll!System.Linq.Enumerable.Aggregate<System.Collections.Generic.List<System.Windows.UIElement>,double>(System.Collections.Generic.IEnumerable<System.Collections.Generic.List<System.Windows.UIElement>> source, double seed, System.Func<double,System.Collections.Generic.List<System.Windows.UIElement>,double> func) + 0xa2 bytes
    Telerik.Windows.Controls.Navigation.dll!Telerik.Windows.Controls.Primitives.TabStripPanel.MeasureOverride(System.Windows.Size availableSize) Line 171 + 0x97 bytes  C#
    PresentationFramework.dll!System.Windows.FrameworkElement.MeasureCore(System.Windows.Size availableSize) + 0x1cc bytes
    PresentationCore.dll!System.Windows.UIElement.Measure(System.Windows.Size availableSize) + 0x1cc bytes
    PresentationCore.dll!System.Windows.ContextLayoutManager.UpdateLayout() + 0x1a1 bytes
    PresentationCore.dll!System.Windows.UIElement.UpdateLayout() + 0x14 bytes
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPane.OnDocumentHostTemplateChanged(System.Windows.DependencyObject sender, System.Windows.DependencyPropertyChangedEventArgs e) Line 1263  C#
    WindowsBase.dll!System.Windows.DependencyObject.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs e) + 0x4d bytes
    PresentationFramework.dll!System.Windows.FrameworkElement.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs e) + 0x50 bytes
    WindowsBase.dll!System.Windows.DependencyObject.NotifyPropertyChange(System.Windows.DependencyPropertyChangedEventArgs args) + 0x3b bytes
    WindowsBase.dll!System.Windows.DependencyObject.UpdateEffectiveValue(System.Windows.EntryIndex entryIndex, System.Windows.DependencyProperty dp, System.Windows.PropertyMetadata metadata, System.Windows.EffectiveValueEntry oldEntry, ref System.Windows.EffectiveValueEntry newEntry, bool coerceWithDeferredReference, bool coerceWithCurrentValue, System.Windows.OperationType operationType) + 0x757 bytes
    WindowsBase.dll!System.Windows.DependencyObject.InvalidateProperty(System.Windows.DependencyProperty dp, bool preserveCurrentValue) + 0xd1 bytes
    PresentationFramework.dll!System.Windows.StyleHelper.InvalidateContainerDependents(System.Windows.DependencyObject container, ref MS.Utility.FrugalStructList<System.Windows.ContainerDependent> exclusionContainerDependents, ref MS.Utility.FrugalStructList<System.Windows.ContainerDependent> oldContainerDependents, ref MS.Utility.FrugalStructList<System.Windows.ContainerDependent> newContainerDependents) + 0xcc bytes
    PresentationFramework.dll!System.Windows.StyleHelper.DoStyleInvalidations(System.Windows.FrameworkElement fe, System.Windows.FrameworkContentElement fce, System.Windows.Style oldStyle, System.Windows.Style newStyle) + 0xcd bytes
    PresentationFramework.dll!System.Windows.StyleHelper.UpdateStyleCache(System.Windows.FrameworkElement fe, System.Windows.FrameworkContentElement fce, System.Windows.Style oldStyle, System.Windows.Style newStyle, ref System.Windows.Style styleCache) + 0x3c bytes
    PresentationFramework.dll!System.Windows.FrameworkElement.OnStyleChanged(System.Windows.DependencyObject d, System.Windows.DependencyPropertyChangedEventArgs e) + 0xd0 bytes
    WindowsBase.dll!System.Windows.DependencyObject.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs e) + 0x4d bytes
    PresentationFramework.dll!System.Windows.FrameworkElement.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs e) + 0x50 bytes
    WindowsBase.dll!System.Windows.DependencyObject.NotifyPropertyChange(System.Windows.DependencyPropertyChangedEventArgs args) + 0x3b bytes
    WindowsBase.dll!System.Windows.DependencyObject.UpdateEffectiveValue(System.Windows.EntryIndex entryIndex, System.Windows.DependencyProperty dp, System.Windows.PropertyMetadata metadata, System.Windows.EffectiveValueEntry oldEntry, ref System.Windows.EffectiveValueEntry newEntry, bool coerceWithDeferredReference, bool coerceWithCurrentValue, System.Windows.OperationType operationType) + 0x757 bytes
    WindowsBase.dll!System.Windows.DependencyObject.InvalidateProperty(System.Windows.DependencyProperty dp, bool preserveCurrentValue) + 0xd1 bytes
    PresentationFramework.dll!System.Windows.FrameworkElement.UpdateStyleProperty() + 0x63 bytes
    PresentationFramework.dll!System.Windows.TreeWalkHelper.InvalidateOnTreeChange(System.Windows.FrameworkElement fe, System.Windows.FrameworkContentElement fce, System.Windows.DependencyObject parent, bool isAddOperation) + 0x3df bytes
    PresentationFramework.dll!System.Windows.FrameworkElement.OnVisualParentChanged(System.Windows.DependencyObject oldParent) + 0x8f bytes
    PresentationCore.dll!System.Windows.Media.Visual.FireOnVisualParentChanged(System.Windows.DependencyObject oldParent) + 0x15 bytes
    PresentationCore.dll!System.Windows.Media.Visual.RemoveVisualChild(System.Windows.Media.Visual child) + 0x6d bytes
    PresentationCore.dll!System.Windows.Media.VisualCollection.DisconnectChild(int index) + 0x60 bytes
    PresentationCore.dll!System.Windows.Media.VisualCollection.RemoveRange(int index, int count) + 0x68 bytes
    PresentationFramework.dll!System.Windows.Controls.UIElementCollection.RemoveRangeInternal(int index, int count) + 0x7f bytes
    PresentationFramework.dll!System.Windows.Controls.Panel.OnItemsChangedInternal(object sender, System.Windows.Controls.Primitives.ItemsChangedEventArgs args) + 0x6e bytes
    PresentationFramework.dll!System.Windows.Controls.Panel.OnItemsChanged(object sender, System.Windows.Controls.Primitives.ItemsChangedEventArgs args) + 0x25 bytes
    PresentationFramework.dll!System.Windows.Controls.ItemContainerGenerator.OnItemRemoved(object item, int itemIndex) + 0x161 bytes
    PresentationFramework.dll!System.Windows.Controls.ItemContainerGenerator.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x9b bytes
    WindowsBase.dll!System.Windows.WeakEventManager.ListenerList<System.Collections.Specialized.NotifyCollectionChangedEventArgs>.DeliverEvent(object sender, System.EventArgs e, System.Type managerType) + 0x12c bytes
    WindowsBase.dll!System.Windows.WeakEventManager.DeliverEvent(object sender, System.EventArgs args) + 0xd6 bytes
    WindowsBase.dll!System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x9 bytes
    PresentationFramework.dll!System.Windows.Data.CollectionView.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x26 bytes
    PresentationFramework.dll!System.Windows.Controls.ItemCollection.OnViewCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x2e bytes
    WindowsBase.dll!System.Windows.WeakEventManager.ListenerList<System.Collections.Specialized.NotifyCollectionChangedEventArgs>.DeliverEvent(object sender, System.EventArgs e, System.Type managerType) + 0x12c bytes
    WindowsBase.dll!System.Windows.WeakEventManager.DeliverEvent(object sender, System.EventArgs args) + 0xd6 bytes
    WindowsBase.dll!System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x9 bytes
    PresentationFramework.dll!System.Windows.Data.CollectionView.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x26 bytes
    PresentationFramework.dll!MS.Internal.Controls.InnerItemCollectionView._RemoveAt(int index, int indexR, object item) + 0x91 bytes
    PresentationFramework.dll!MS.Internal.Controls.InnerItemCollectionView.Remove(object item) + 0x3e bytes
    PresentationFramework.dll!System.Windows.Controls.ItemCollection.Remove(object removeItem) + 0x1c bytes
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPaneGroup.CloseSinglePane(Telerik.Windows.Controls.RadPane pane) Line 1331 + 0x18 bytes    C#
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPaneGroup.ClosePane(Telerik.Windows.Controls.RadPane pane) Line 622 + 0xc bytes    C#
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadDocking.OnPaneClose(Telerik.Windows.Controls.RadPane pane) Line 875    C#
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadDocking.OnRadPaneClose(object sender, Telerik.Windows.Controls.Docking.StateChangeCommandEventArgs args) Line 840 + 0x14 bytes C#
    [Native to Managed Transition]
    mscorlib.dll!System.Delegate.DynamicInvokeImpl(object[] args) + 0x76 bytes
    PresentationCore.dll!System.Windows.RoutedEventArgs.InvokeEventHandler(System.Delegate genericHandler, object genericTarget) + 0x97 bytes
    PresentationCore.dll!System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate handler, object target) + 0x33 bytes
    PresentationCore.dll!System.Windows.RoutedEventHandlerInfo.InvokeHandler(object target, System.Windows.RoutedEventArgs routedEventArgs) + 0x44 bytes
    PresentationCore.dll!System.Windows.EventRoute.InvokeHandlersImpl(object source, System.Windows.RoutedEventArgs args, bool reRaised) + 0x12f bytes
    PresentationCore.dll!System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject sender, System.Windows.RoutedEventArgs args) + 0x73 bytes
    PresentationCore.dll!System.Windows.UIElement.RaiseEvent(System.Windows.RoutedEventArgs e) + 0x29 bytes
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPane.RaiseEventInternal(Telerik.Windows.RadRoutedEventArgs args) Line 1543 + 0xe bytes C#
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPane.OnClose(Telerik.Windows.Controls.Docking.StateChangeCommandEventArgs args) Line 1314  C#
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPane.Close() Line 1393 + 0x2c bytes    C#
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPane.OnIsHiddenChanged(System.Windows.DependencyObject d, System.Windows.DependencyPropertyChangedEventArgs e) Line 1225 + 0xb bytes   C#
    WindowsBase.dll!System.Windows.DependencyObject.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs e) + 0x4d bytes
    PresentationFramework.dll!System.Windows.FrameworkElement.OnPropertyChanged(System.Windows.DependencyPropertyChangedEventArgs e) + 0x50 bytes
    WindowsBase.dll!System.Windows.DependencyObject.NotifyPropertyChange(System.Windows.DependencyPropertyChangedEventArgs args) + 0x3b bytes
    WindowsBase.dll!System.Windows.DependencyObject.UpdateEffectiveValue(System.Windows.EntryIndex entryIndex, System.Windows.DependencyProperty dp, System.Windows.PropertyMetadata metadata, System.Windows.EffectiveValueEntry oldEntry, ref System.Windows.EffectiveValueEntry newEntry, bool coerceWithDeferredReference, bool coerceWithCurrentValue, System.Windows.OperationType operationType) + 0x757 bytes
    WindowsBase.dll!System.Windows.DependencyObject.SetValueCommon(System.Windows.DependencyProperty dp, object value, System.Windows.PropertyMetadata metadata, bool coerceWithDeferredReference, bool coerceWithCurrentValue, System.Windows.OperationType operationType, bool isInternal) + 0x2ea bytes
    WindowsBase.dll!System.Windows.DependencyObject.SetValue(System.Windows.DependencyProperty dp, object value) + 0x35 bytes
    Telerik.Windows.Controls.Docking.dll!Telerik.Windows.Controls.RadPane.IsHidden.set(bool value) Line 326 + 0x28 bytes    C#
    ShowDesigner.exe!Monogram.Sport.ShowDesigner.Assets.DockingExtensions.PaneSource_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) Line 122 + 0xf bytes   C#
    PresentationFramework.dll!System.Windows.Data.CollectionView.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x26 bytes
    PresentationFramework.dll!MS.Internal.Data.CompositeCollectionView.OnContainedCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x4cc bytes
    PresentationFramework.dll!System.Windows.Data.CompositeCollection.OnContainedCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x13 bytes
    WindowsBase.dll!System.Windows.WeakEventManager.ListenerList<System.Collections.Specialized.NotifyCollectionChangedEventArgs>.DeliverEvent(object sender, System.EventArgs e, System.Type managerType) + 0x12c bytes
    WindowsBase.dll!System.Windows.WeakEventManager.DeliverEvent(object sender, System.EventArgs args) + 0xd6 bytes
    WindowsBase.dll!System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x9 bytes
    PresentationFramework.dll!System.Windows.Data.CollectionContainer.OnContainedCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x15 bytes
    PresentationFramework.dll!System.Windows.Data.CollectionContainer.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0xe bytes
    WindowsBase.dll!System.Windows.WeakEventManager.ListenerList<System.Collections.Specialized.NotifyCollectionChangedEventArgs>.DeliverEvent(object sender, System.EventArgs e, System.Type managerType) + 0x12c bytes
    WindowsBase.dll!System.Windows.WeakEventManager.DeliverEvent(object sender, System.EventArgs args) + 0xd6 bytes
    WindowsBase.dll!System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x9 bytes
    PresentationFramework.dll!System.Windows.Data.CollectionView.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x26 bytes
    PresentationFramework.dll!System.Windows.Data.ListCollectionView.ProcessCollectionChangedWithAdjustedIndex(System.Collections.Specialized.NotifyCollectionChangedEventArgs args, int adjustedOldIndex, int adjustedNewIndex) + 0x297 bytes
    PresentationFramework.dll!System.Windows.Data.ListCollectionView.ProcessCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x12d bytes
    PresentationFramework.dll!System.Windows.Data.CollectionView.OnCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x3c bytes
    System.dll!System.Collections.ObjectModel.ReadOnlyObservableCollection<System.__Canon>.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x17 bytes
    System.dll!System.Collections.ObjectModel.ReadOnlyObservableCollection<System.__Canon>.HandleCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0xe bytes
    System.dll!System.Collections.ObjectModel.ObservableCollection<Monogram.Sport.ShowDesigner.Infrastructure.DocumentTab>.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x48 bytes
    System.dll!System.Collections.ObjectModel.ObservableCollection<System.__Canon>.RemoveItem(int index) + 0x9f bytes
    mscorlib.dll!System.Collections.ObjectModel.Collection<Monogram.Sport.ShowDesigner.Infrastructure.DocumentTab>.Remove(Monogram.Sport.ShowDesigner.Infrastructure.DocumentTab item) + 0x6c bytes
    ShowDesigner.Infrastructure.dll!Monogram.Sport.ShowDesigner.Infrastructure.WorkspaceService.CloseDocument(Monogram.Sport.ShowDesigner.Infrastructure.DocumentTab document, bool forceClose) Line 118 + 0x10 bytes   C#
>   ShowDesigner.exe!Monogram.Sport.ShowDesigner.MainWindow.MainWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e) Line 134 + 0x17 bytes    C#

Using version 2012.3.1017.45

[Alek]

Hi Daniel,

The information you've sent us is insufficient and we cannot have the final statement what is the cause for the exception. 

Please, sent us a sample project in order to investigate the issue.

Regards, Alek
the Telerik team

[Daniel]

I've tried do create sample project but I was unable to reproduce the exception in sample project :/

Do you think, it could be related to the content of RadPane, according the posted callstack?

[Alek]

Hi Daniel,

Regarding the content  - yes, it is possible. When you are hiding the RadPane the content is putted out of the visual tree and depending how your application is written this may cause the described behavior. 

Following the statement that you can not reproduce the issue we can suggest you the following - if it's possible, try to cut parts of the code until the application stops to throw the exception. This will help you to track the issue.

Kind regards, Alek
the Telerik team