Microsoft.Windows.Controls.Ribbon.RibbonGalleryCategory.OnItemsChanged C# (CSharp) Method

        protected override void OnItemsChanged(NotifyCollectionChangedEventArgs e)
        {
            switch (e.Action)
            {
                case NotifyCollectionChangedAction.Remove:
                case NotifyCollectionChangedAction.Replace:
                    if (RibbonGallery != null)
                    {
                        object selectedItem = RibbonGallery.SelectedItem;
                        object highlightedItem = RibbonGallery.HighlightedItem;
                        if (selectedItem != null || highlightedItem != null)
                        {
                            for (int i = 0; i < e.OldItems.Count; i++)
                            {
                                if (selectedItem != null && RibbonGallery.VerifyEqual(selectedItem, e.OldItems[i]))
                                {
                                    // Synchronize SelectedItem if it is one of
                                    // the items being removed or replaced.
                                    RibbonGallery.ForceCoerceSelectedItem();
                                    break;
                                }
                                if (highlightedItem != null && RibbonGallery.VerifyEqual(highlightedItem, e.OldItems[i]))
                                {
                                    // Synchronize HighlightedItem if it is one of
                                    // the items being removed or replaced.
                                    RibbonGallery.ForceCoerceHighlightedItem();
                                    break;
                                }
                            }
                        }
                        RibbonGallery.IsMaxColumnWidthValid = false;
                    }
                    break;
                case NotifyCollectionChangedAction.Reset:
                    if (RibbonGallery != null)
                    {
                        if (RibbonGallery.SelectedItem != null)
                        {
                            // Synchronize SelectedItem after a Reset operation.
                            RibbonGallery.ForceCoerceSelectedItem();
                        }
                        if (RibbonGallery.HighlightedItem != null)
                        {
                            // Synchronize HighlightedItem after a Reset operation.
                            RibbonGallery.ForceCoerceHighlightedItem();
                        }

                        RibbonGallery.IsMaxColumnWidthValid = false;
                    }
                    break;

                case NotifyCollectionChangedAction.Add:
                    if (RibbonGallery != null)
                    {
                        RibbonGallery.IsMaxColumnWidthValid = false;
                    }
                    break;
                case NotifyCollectionChangedAction.Move:
                    break;
            }
        }