Great feature: I like it.
But... the current implementation (in PortletModeDropDownTag) has now broken the Admin portlets
I've spend quite a lot of time trying to find out what was wrong and its still now 100% clear to me, but it has to do with the "anonymous" <form style="display:inline" ...> you emit from the tag for it.
The Admin portlet uses and references its "adminForm", but together with the PortletModeDropDownTag this doesn't work anymore (document.forms['adminForm'] unknown).
NB: I've been testing with Firefox 3.0 (Ubuntu).
Can you please look into this?