demo: clearfix the #nav element
add 'open' and 'close' settings

This allows you to take control over how jquery-dropdown opens and
closes a menu with your own callback function. If either one is passed
to .dropdown(), it will override the default action (setting the
display: property on the ul inside the target element).

--HG--
extra : amend_source : f43839e27d64ba327f2d3942189a9e636827e00a