internal void GetGlobalItems(List <object> items) { if (this.IsBottomLevel) { items.AddRange(this.ProtectedItems); return; } int count = this.ItemCount; for (int i = 0; i < count; i++) { DataGridCollectionViewGroup subGroup = this.ProtectedItems[i] as DataGridCollectionViewGroup; if (subGroup == null) { throw new InvalidOperationException("Sub-groups cannot be null (Nothing in Visual Basic)."); } subGroup.GetGlobalItems(items); } }