true once this render has been superseded. A cheap guard for consumers
doing non-abortable work, so they can bail out between steps without
touching RenderContext.signal.
Which pivot is running.
ReadonlysignalAborted when this render is superseded — the tooltip hid or reopened for
another element, the selection changed, the panel was refreshed or
removed, the graph was destroyed. Forward it to fetch and in-flight
requests are cancelled instead of leaked.
Handed to both provider calls as the last argument. Extends RenderContext, so cancellation works the way it does everywhere else: forward
signaltofetch, or pollisStale()between steps.