tinymce.dom.AriaAnnouncer
Page-wide aria-live announcer used to send messages to screen readers without shifting focus. Messages are appended as child divs to one of two persistent live regions, polite or assertive (both aria-atomic="false", aria-relevant="additions"), so each child is announced independently as it is added. Earlier messages remain in the DOM and are not re-read. Each message is removed after a delay long enough for screen readers to have picked up the mutation, keeping the regions bounded over long sessions. The polite and assertive regions differ only in their aria-live politeness: assertive announcements interrupt the screen reader’s current speech, while polite ones wait for it to finish.