5f545dbde8
This commit is an experiment in using popovers as a place to house some of the filtering options for animation editors, in line with what's taking place in the Outliner with the filtering popover there too. Right now, the most frequently used/changed options are still available on the headers (i.e. the "Only Selected"/"Hidden"/search fields), while everything else (i.e. the per-datablock filters, which were already hidden behind a collapsed-toggle button before) now live in the popover.