open popup to close, update div in parent window?

i have a form where a user can open a popup to add categories. when the
window is closed, id like the dropdown list in the form to get refreshed
via rjs.

however, i am having trouble updating the drop down since i cant seem to
access the div id in the parent window from the popup. anyone know how?


If you're planning on using RJS already, why not have the 'close'
method send the categories to the server, and then the server can
build up the <options> and send them down to the browser?