i am creating a usercontrol which provides all of the common validations for a range of textbox styles: alpha, number, decimal, SSN, etc. so, when a developer using this control selects the alpha style, they can also select another property which defines a string of special characters that could also be allowed during validation. but when the decimal style, for instance, is selected, i'd like to simply disable the special characters property so it is not settable when a style is selected that doesn't allow special characters. how can i achieve this goal? thanks