gistfile1.cs

        private bool customPref_PreferenceClick(Preference preference)
        {
            IEnumerable<char>[] stockItemsDisplay = _stockItemsConfig.OrderBy(i => i.StockDataItem).Select(i => i.StockDataItem.GetStringValue()).ToArray();
            bool[] allitemschecked = _stockItemsConfig.OrderBy(i => i.StockDataItem).Select(i => i.IsChecked).ToArray();
            
            var dialog = new AlertDialog.Builder(this);
            dialog.SetMultiChoiceItems(stockItemsDisplay, allitemschecked, clickCallback);
            dialog.SetTitle("Select columns");
            dialog.SetPositiveButton("Save", saveCallback);
            dialog.Create().Show();
            return true;
        }