Confirmation overlays display a temporary message expressing a state change at the top of the current view.
Usage
Confirmation overlays are available in three variations: confirmation, failure, and open on phone.
Confirmation
In most cases, an explicit confirmation is not needed. A visible change in the UI is enough to show that an action succeeded. If the user’s action is not visible in the UI, use the confirmation overlay to give the necessary feedback to the user. It's better to show a change in the UI itself rather than showing a confirmation overlay.
Do
Add a message to your message history instead of showing a confirmation overlay.
Do
Show a confirmation overlay if a change in action doesn't cause a change in the UI.
Failure
Do
Display a failure message when a process fails.
Open on phone
Do
Display a confirmation when an activity triggered from a wearable device is opened on a phone.