This is easily a dhtml issue, or one that can likely be performed in
rjs. (repopulating 'b') when someting occurs. Additionally, here is
working code I use to pick up when a dropdown's selection has changed:
It;s a little polluted with real-world dictates, but I dont want to
hack things out for trhis example and give you a broken example
inadvertently. The meat occurs in the :onchange where the form is
submitted in this case (when the user changes their selection).
Incidentally, this occurs in a partial, which then executes the
Channelscontroller.newchannel method. Perhaps you make a partial
holding dropdown 'b' and repopulate it in such a method? That should
work fine -Janna B