OverlayEntry constructor
Creates an overlay entry.
To insert the entry into an Overlay, first find the overlay using Overlay.of and then call OverlayState.insert. To remove the entry, call remove on the overlay entry itself.
Implementation
OverlayEntry({
@required this.builder,
bool opaque = false,
bool maintainState = false,
}) : assert(builder != null),
assert(opaque != null),
assert(maintainState != null),
_opaque = opaque,
_maintainState = maintainState;