This avoids it ever mutating the underlying track (aka attempting to start
it). Resolves the one caveat mentioned in
aeef92fa710648d4a00edc523e13c17ac6104125.
The new implementation of `DecouplingClock` will not mutate the
underlying clock in any way (unless attempting to start it when
approaching from a negative time value).
This should be quite safe as a result.
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.