initialEntries property
final
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.insert or OverlayState.insertAll.
To remove an entry from an Overlay, use OverlayEntry.remove.
Implementation
final List<OverlayEntry> initialEntries;