llback changes the underlying data structure
    then asks the interface to refresh. This might mean that things update in the
interface that don't need to, but ensures the callbacks remain simple and that all
interface update logic is in one place. Extending this to more granular interface updates
            is straightforward. See <a href="demoBrowserScalability.html">Scalability</a> for more details.</p>
            <p>For the listbox callback, the "src" argument is a handle to the
            listbox a