System.Web.UI.WebControls.ListBox.VerifyMultiSelect C# (CSharp) Method

        protected internal override void VerifyMultiSelect()
        {
            //by default the ListControl will throw an exception in this method,
            //therefor we should override the method if the class is supporting
            //MultiSelect option.
            if (this.SelectionMode != ListSelectionMode.Multiple)
                throw new HttpException("Multiple select option is not supported");
        }
#endif