Basic styling component to render UI content just below a <Pane>'s header.
Pass in as the subheader prop of <Pane> component;
const sbh = (
<PaneSubheader>
<SegmentedControl activeId="instanceLevel">
<Button id="instanceLevel">Instance</Button>
<Button id="holdingsLevel">Holdings</Button>
<Button id="itemsLevel">Items</Button>
</SegmentedControl>
</PaneSubheader>
);
...
<Pane id="pane-instancedetails" subheader={sbh} > ...