Make alerts accessible
From Clare comes a problem statement and some brainstorming ideas:
A problem for our low vision users is alerts, their AT software doesn't recognise them, so they miss warnings and end up adding duplicates. It would be great to have some sort of per user control for setting how alerts display, perhaps even adding audio cues.
Use alert role approach suggested at https://www.w3.org/TR/2017/NOTE-wai-aria-practices-1.1-20171214/examples/alert/index.html as this will allow audio cues to be given to users of screen readers.
Note more details at https://www.w3.org/TR/2017/NOTE-wai-aria-practices-1.1-20171214/#alert and also https://www.w3.org/TR/2017/NOTE-wai-aria-practices-1.1-20171214/#alertdialog
https://www.w3.org/TR/UNDERSTANDING-WCAG20/time-limits-no-exceptions.html indicates that there should be no time limits like quickly disappearing alerts.
As a first pass, let's implement a site wide setting to disable alerts from disappearing. We don't have a good design pattern currently for per user preferences. When we do move to per user preferences, the default should be to have alerts not disappear.