In testing, some users have had trouble at first finding the main filtering dropdown. Part of the problem seems to come from the fact that they don't all think of themselves as searching, per se, for changes. So they don't click into the search bar.
To make it more apparent that clicking in the bar will produce a menu, we will switch the magnifying glass to a hamburger menu when the filter panel is not shown, keeping the search icon when any filter panel is open in order to invite users to search.
To see how this works in action try it live in this prototype