NullReference when removing ContentControl containing SfTreeView

[John]

So, I use DockingManager and have ContentControl window that has a SfTreeView. I basically have a tabbed layout and whenever I close a tab I go though and dispose the ContentControl/tree view and then remove it from DockingManager.Children. The Contains API returns true so my window is one of the Children but when I call remove I get a NullReference exception. Wasn't there a problem like this recently with one of the Grids? I don't interact at all with selection background color. And I don't have this problem with any of my other windows. I have others that use SfDataGrid, SfTreeGrid, and some others and they work fine using the same approach.

   at Syncfusion.UI.Xaml.TreeView.SfTreeView.OnSelectionBackgroundColorChanged(Object oldValue, Object newValue)

   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.DependencyObject.InvalidateProperty(DependencyProperty dp)
   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.DependencyObject.InvalidateProperty(DependencyProperty dp)
   at System.Windows.FrameworkElement.UpdateStyleProperty()
   at System.Windows.TreeWalkHelper.InvalidateStyleAndReferences(DependencyObject d, ResourcesChangeInfo info, Boolean containsTypeOfKey)
   at System.Windows.TreeWalkHelper.OnResourcesChanged(DependencyObject d, ResourcesChangeInfo info, Boolean raiseResourceChangedEvent)
   at System.Windows.FrameworkElement.OnAncestorChangedInternal(TreeChangeInfo parentTreeState)
   at System.Windows.TreeWalkHelper.OnAncestorChanged(DependencyObject d, TreeChangeInfo info, 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 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 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 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 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.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.ChangeLogicalParent(DependencyObject newParent)
   at System.Windows.FrameworkElement.RemoveLogicalChild(Object child)
   at Syncfusion.Windows.Tools.Controls.LogicalElementCollection.ClearLogicalParent(FrameworkElement element)
   at Syncfusion.Windows.Tools.Controls.LogicalElementCollection.Remove(FrameworkElement element)
   at EQLogParser.SyncFusionUtil.<>c__DisplayClass1_0.b__0() in C:\Users\kauff\code\github\EQLogParser\EQLogParser\src\ui\util\SyncFusionUtil.cs:line 31

[Santhosh Govindasamy]

Hi John,

​
We are currently analyzing the scenario you reported. We need time to validate it, and we will provide an update on or before September 22, 2023.

Regards,
Santhosh.G

[Santhosh Govindasamy]

Hi John,

We have some uncertainties regarding the disposal process when closing a tab, as well as information related to tab layout within the docking manager. Could you please provide details on the removal process and instructions on utilizing the tab layout feature? Your assistance in clarifying these points will enable us to review and offer a solution promptly.

Regards,
Santhosh.G