1429263 - Prevent further payment request dialog changes while waiting for change responses

Status: NEW

(Firefox :: WebPayments UI, enhancement, P3)

Description

[Matthew N. [:MattN]]

When the "PaymentRequest updated algorithm" runs to dispatch an event to notify the merchant of a change, the payment request dialog shouldn't allow further changes until the response to first change was received in order to avoid UI becoming inconsistent with the merchant state.

See `event.[[waitForUpdate]]`[1] and `request.[[updating]]`[2]

[1] https://w3c.github.io/payment-request/#dfn-waitforupdate
[2] https://w3c.github.io/payment-request/#dfn-updating

Comment 1

[Matthew N. [:MattN]]

Bug 1429205 implemented a basic overlay but doesn't fully prevent using buttons behind the overlay. Some things we should do:
* prevent tabbing to controls behind the overlay
* ensure screen readers don't read the hidden contents e.g. @aria-disabled
* ensure elements that are already focused aren't usable with the keyboard or mouse

Comment 2

[Jared Wein [:jaws] (please needinfo? me)]

This bug should also cover not running validation until the update has completed.

Comment 3

[Eric Pang [:epang] UX]

Attachment: validation-delay.png

Visuals of what should happen on a validation delay.

When validation occurs on click of a navigation button the loading indicator appears in the button with a 80% white overlay behind. 

When from a picker or without a button the loading indicator is centered on top of a 80% white overlay.