This object is returned by customer's PSPDFKit.CustomUIRendererCallback functions to enhance the default appearance of a UI element.
Its main, fundamental property is
node, which is the DOM node that will be appended to the container node.
Optionally it can contain an
onRenderItem event handler, which is called for each item in the list.
DOM node to be appended to the container, if different from
Callback to be called whenever an item is rendered.