If non-null, whether the node should be considered a live region.
On Android, when a live region semantics node is first created TalkBack will make a polite announcement of the current label. This announcement occurs even if the node is not focused. Subsequent polite announcements can be made by sending a UpdateLiveRegionEvent semantics event. The announcement will only be made if the node's label has changed since the last update.
On iOS, no announcements are made but the node is marked as
An example of a live region is the
Snackbar widget. When it appears
on the screen it may be difficult to focus to read the label. A live
region causes an initial polite announcement to be generated
final bool liveRegion