private void SetSelectedItemsOnDropDown() { if (SelectedItems != null) { SelectedItems.Clear(); } SelectedItems = (IList)Activator.CreateInstance(SelectedItems.GetType()); if (this.ItemsSource.Count > 0) { int index = 0; foreach (var item in _itemList) { if (item.IsSelected) { SelectedItems.Add(ItemsSource[index]); } index++; } } }