An overlay widgets renders on top of the text.
Optional
Render this overlay widget in a location where it could overflow the editor's view dom node.
Get the dom node of the overlay widget.
Get a unique identifier of the overlay widget.
The editor will ensure that the scroll width is >= than this value.
Get the placement of the overlay widget. If null is returned, the overlay widget is responsible to place itself.
An overlay widgets renders on top of the text.