Add role="group" to transcript focusable (#3765)

CHANGELOG.md

@@ -67,6 +67,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 -  Fixes [#3747](https://github.com/microsoft/BotFramework-WebChat/issues/3747). `aria-pressed` and `aria-role` is not properly set on Adaptive Cards submit buttons, by [@amal-khalaf](https://github.com/amal-khalaf) in PR [#3744](https://github.com/microsoft/BotFramework-WebChat/pull/3744)
 -  Fixes [#3750](https://github.com/microsoft/BotFramework-WebChat/issues/3750). Debump Node.js engines requirements for some packages to `12.0.0`, by [@compulim](https://github.com/compulim) in PR [#3753](https://github.com/microsoft/BotFramework-WebChat/pull/3753)
 -  Fixes [#3760](https://github.com/microsoft/BotFramework-WebChat/issues/3760). Use `<ErrorBoundary>` to wrap around attachment renderer, by [@compulim](https://github.com/compulim) in PR [#3761](https://github.com/microsoft/BotFramework-WebChat/pull/3761)
+-  Fixes [#3764](https://github.com/microsoft/BotFramework-WebChat/issues/3764). Added `role="group"` to the focusable transcript to enable `aria-activedescendant`, by [@compulim](https://github.com/compulim) in PR [#3765](https://github.com/microsoft/BotFramework-WebChat/issues/3765)
 
 ### Changed
 

packages/component/src/BasicTranscript.js

@@ -743,6 +743,9 @@ const InternalTranscript = ({ activityElementsRef, className }) => {
       onKeyDown={handleTranscriptKeyDown}
       onKeyDownCapture={handleTranscriptKeyDownCapture}
       ref={rootElementRef}
+      // "aria-activedescendant" will only works with a number of roles and it must be explicitly set.
+      // https://www.w3.org/TR/wai-aria/#aria-activedescendant
+      role="group"
       // For up/down arrow key navigation across activities, this component must be included in the tab sequence.
       // Otherwise, "aria-activedescendant" will not be narrated when the user press up/down arrow keys.
       // https://www.w3.org/TR/wai-aria-practices-1.1/#kbd_focus_activedescendant