Semantics Order of the Overlay Entries in Modal Routes

Summary

Context

Description of change

Migration guide

Timeline

References

Summary

We changed the semantics traverse order of the overlay entries in modal routes.
Accessibility talk back or voice over now focuses the scope of a modal route
first instead of its modal barrier.

Context

The modal route has two overlay entries, the scope and the modal barrier. The
scope is the actual content of the modal route, and the modal barrier is the
background of the route if its scope does not cover the entire screen. If the
modal route returns true for barrierDismissible, the modal barrier becomes
accessibility focusable because users can tap the modal barrier to pop the
modal route. This change specifically made the accessibility to focus the scope
first before the modal barrier.

Description of change