Portal class

The widget where a PortalTarget and its PortalFollower are rendered.

Portal can be considered as a reimplementation of Overlay to allow adding an OverlayEntry (now named PortalTarget) declaratively.

The Portal widget is used in coordination with the PortalTarget widget to show some content above other content. This is similar to Stack in principle, with the difference that a PortalTarget does not have to be a direct child of Portal and can instead be placed anywhere in the widget tree.

In most situations, Portal can be placed directly above MaterialApp:

Portal(
  child: MaterialApp(
  ),
);

This allows an overlay to render above everything including all routes. That can be useful to show a snackbar between pages.

You can optionally add a Portal inside your page:

Portal(
  child: Scaffold(
  ),
)

This way, your modals/snackbars will stop being visible when a new route is pushed.