The overlay on the map that is selected.
To deselect any currently selected overlay, set this attribute to
To select an overlay that is already part of the map, set this attribute to the desired overlay.
When the selected overlay is removed from the map (as an effect of
removeOverlays, or setting a new set of overlays with the
overlays property), it is deselected before being removed.
Adding and Removing Overlays
An array of all of the map's overlays.
Returns an array of overlays at a given point on the webpage.