Microsoft.Windows.Controls.Ribbon.RibbonGallery.CoerceSelectedItem C# (CSharp) Метод

        private static object CoerceSelectedItem(DependencyObject d, object value)
        {
            RibbonGallery gallery = (RibbonGallery)d;

            if (!gallery.IsSelectionChangeActive)
            {
                object oldItem = gallery.SelectedItem;
                object newItem = value;

                if (!VerifyEqual(oldItem, newItem))
                {
                    if (newItem != null)
                    {
                        RibbonGalleryCategory category = null;
                        RibbonGalleryItem galleryItem = null;

                        // If the newItem doesn't exist in RibbonGallery under any category then return UnsetValue
                        // so as not to change existing value
                        bool ignoreItemContainerGeneratorStatus = false;
                        if (!gallery.ContainsItem(newItem, ignoreItemContainerGeneratorStatus, out category, out galleryItem))
                        {
                            return DependencyProperty.UnsetValue;
                        }

                        // Changes the selection to newItem
                        gallery.ChangeSelection(newItem, galleryItem, true);
                    }
                    else
                    {
                        // Deselect oldItem
                        gallery.ChangeSelection(oldItem, null, false);
                    }
                }
                else if (gallery.ShouldForceCoerceSelectedItem)
                {
                    RibbonGalleryCategory category = null;
                    RibbonGalleryItem galleryItem = null;

                    // This block is called when ItemCollection changes either at the Gallery or the Category levels
                    // to handle the case that a previously SelectedItem is removed or replaced.
                    bool ignoreItemContainerGeneratorStatus = true;
                    if (!gallery.ContainsItem(newItem, ignoreItemContainerGeneratorStatus, out category, out galleryItem))
                    {
                        // Deselect oldItem
                        value = null;
                        gallery.ChangeSelection(oldItem, null, false);
                    }
                }
            }

            return value;
        }