Active interactions. Ensure that all active interactions do
something. Any button that can
be pushed should do something when pushed. For example, if you have a
no-op callback for an onPressed event, change it to show a SnackBar
on the screen explaining which control you just pushed.

Screen reader testing. The screen reader should be able to
describe all controls on the page when you tap on them, and the
descriptions should be intelligible. Test your app with TalkBack
(Android) and VoiceOver (iOS).

Contrast ratios. We encourage you to have a contrast ratio of at
least 4.5:1 between controls or text and the background, with the
exception of disabled components. Images should also be vetted for
sufficient contrast.

Context switching. Nothing should change the user’s context
automatically while typing in information. Generally, the widgets
should avoid changing the user’s context without some sort of
confirmation action.