With popover usage now only passing in React Components, the
logic of removing the popover and recreating its html with
every update is not necessary. Instead allow React to update
the popover contents.
Because of this change, mouse event handlers are not recreated
on each update, so it is possible for mouseleave to fire after
the size of the popover shrinks when collapsing to hide more stats,
forcing the mouse out of the popover. To prevent this, padding has
been added to the top of the popover so on resize the mouse will
still be over the popover. The padding has the added bonus of
fixing an issue where the popover would not close until mouseenter
was triggered after size collapse, but it adds the drawback of
requiring more upward mouse travel to close the popover.
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