QuickForm: Event on Element to change other elements

Hi I have a form with some selct-boxes. What I want is tte following: the user should only be alloewd to select from one select-box. So if for example some items in a particular select-box are selected, they should be unselected when the user selects items from another select-box. Is there a way to do that in QuickForm or do I need to engage some javascript therefore? Any hints and tips are appreciated! Thanks! -- Regards Marco