Wanting to use this inside notification, it turns out that the original
design did not work very well at such narrow widths, and additionally
the typical button setup borrowed from elsewhere resulted in teeny tiny
action buttons.
To that end, slim down the design (get rid of thumbnail, audio preview,
make expandable right side slimmer), as well as change the entire panel
so that it has only one action associated with it at all times, and
clicking the panel in any place triggers that action.