overlays property
Layers displayed above the content.
These layers are placed at the same (x,y) as content, and they're forced to layout at the exact same size as content.
Layers are structured as WidgetBuilders so that they can be re-built whenever the content layout changes, without interference from Flutter's standard build system. Ideally, layers would be pure Widgets, but this is a consequence of how Flutter's BuildOwner works. For more details, see https://github.com/flutter/flutter/issues/123305 and https://github.com/superlistapp/super_editor/pull/1239
Implementation
final List<ContentLayerWidgetBuilder> overlays;