follow a path (specifically, I want to allow the media panel to be "scrolled" along a path). git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@1409 542714f4-19e9-0310-aa3c-eee0fc999fb1
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@543 542714f4-19e9-0310-aa3c-eee0fc999fb1