Microsoft.Windows.Controls.Ribbon.RibbonGallery.OnCurrentItemChanged C# (CSharp) Method

        private void OnCurrentItemChanged()
        {
            Debug.Assert(IsSynchronizedWithCurrentItemInternal, "We shouldn't be listening for currency changes if IsSynchronizedWithCurrentItemInternal is false");

            if (CollectionView == null || IsSelectionChangeActive)
            {
                return;
            }

            // Synchronize the SelectedItem to be the first Item
            // within the current Category.
            RibbonGalleryCategory category = this.ItemContainerGenerator.ContainerFromItem(CollectionView.CurrentItem) as RibbonGalleryCategory;
            if (category != null && category.Items.Count > 0)
            {
                SelectedItem = category.Items[0];
            }
        }