This is the most logged exception in my application and it looks like it's coming from RadToolBar: Specified element is already the logical child of another element. Disconnect it first.
Stacktrace:
System.Windows.FrameworkElement.ChangeLogicalParent(DependencyObject newParent):50
System.Windows.FrameworkElement.AddLogicalChild(Object child):55
System.Windows.Controls.UIElementCollection.AddInternal(UIElement element):7
System.Windows.Controls.UIElementCollection.Add(UIElement element)
Telerik.Windows.Controls.RadToolBar.InsertInPanel(Panel panel, UIElement container, Int32 position):3
Telerik.Windows.Controls.RadToolBar.OnItemsCollectionChanged(Panel panel, NotifyCollectionChangedEventArgs e):136
Telerik.Windows.Controls.RadToolBar.OnOverflowItemsCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e):15
System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, T item):36
System.Collections.ObjectModel.Collection`1.Add(T item):32
System.Collections.ObjectModel.Collection`1.System.Collections.IList.Add(Object value):28
Telerik.Windows.Controls.RadToolBar.InsertOverflowItem(Object item, Int32 position):45
Telerik.Windows.Controls.RadToolBar.TryMoveStripItemToOverflow(Int32 index)
Telerik.Windows.Controls.RadToolBar.MeasureOverride(Size availableSize):70
System.Windows.FrameworkElement.MeasureCore(Size availableSize):568
System.Windows.UIElement.Measure(Size availableSize):401
System.Windows.Controls.Grid.MeasureOverride(Size constraint):67
System.Windows.FrameworkElement.MeasureCore(Size availableSize):568
System.Windows.UIElement.Measure(Size availableSize):401
System.Windows.Controls.Border.MeasureOverride(Size constraint):256
System.Windows.FrameworkElement.MeasureCore(Size availableSize):568
System.Windows.UIElement.Measure(Size availableSize):401
MS.Internal.Helper.MeasureElementWithSingleChild(UIElement element, Size constraint):28