Creates a new overlay, and inserts it into the DOM as soon as waitForMutateTime resolves, or returns an already existing matching overlay.
Note that if OverlayOptions.id is set, a new overlay will always be created.
Optional
Creates a new overlay, and inserts it into the DOM as soon as waitForMutateTime resolves, or returns an already existing matching overlay.
Note that if OverlayOptions.id is set, a new overlay will always be created.