Microsoft.Phone.Controls.ListPicker.OnSelectedIndexChanged C# (CSharp) Method

        private void OnSelectedIndexChanged(int oldValue, int newValue)
        {
            // Validate new value
            if ((Items.Count <= newValue) ||
                ((0 < Items.Count) && (newValue < 0)) ||
                ((0 == Items.Count) && (newValue != -1)))
            {
                if ((null == Template) && (0 <= newValue))
                {
                    // Can't set the value now; remember it for later
                    _deferredSelectedIndex = newValue;
                    return;
                }
            }

            // Synchronize SelectedItem property
            if (!_updatingSelection)
            {
                _updatingSelection = true;
                SelectedItem = (-1 != newValue) ? Items[newValue] : null;
                _updatingSelection = false;
            }

            if (-1 != oldValue)
            {
                // Toggle container selection
                ListPickerItem oldContainer = (ListPickerItem)ItemContainerGenerator.ContainerFromIndex(oldValue);
                if (null != oldContainer)
                {
                    oldContainer.IsSelected = false;
                }
            }
        }