usePolled reports when a request is in flight (through a new onBusy of the
poller) and holds it on for at least 0.4 seconds, so a quick answer still
reads as a refresh. The picker swaps its clock for the spinner, in the same
box so its width stays, and the spinner stands still where motion is off.
Every page with a picker passes it; a page with several polled requests shows
it while any of them runs. The Jobs page fetches through shared components
and has none yet.
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