read-only
The entries to include in the overlay initially.
These entries are only used when the OverlayState is initialized. If you are providing a new Overlay description for an overlay that's already in the tree, then the new entries are ignored.
To add entries to an Overlay that is already in the tree, use
Overlay.of to obtain the OverlayState (or assign a GlobalKey to the
Overlay widget and obtain the OverlayState via
GlobalKey.currentState), and then use OverlayState.add or
OverlayState.addAll.
To remove an entry from an Overlay, use OverlayEntry.remove.