You have to go to Studio => Apps => updates, I suggest you to check regularly, all the updates are there. Also, when you have applied an update, go back to see if there is not a next one, they are proposed successively. For the moment nothing attracts the eye there when an update is available but it will be done in a next update, good thing!
1. The presentation of the connection status has been reviewed, it is now visually standardized AND synchronized with the site. We can sell his glasses ;-) 2. You are now notified if your last message has been read. 3. You can now edit your last message with the up arrow key. 4. The conversation files are now accessible in a dedicated drawer. (see new option 'i' => files) 5. Auto-saved messages: When you start typing a message, you can now switch windows and come back to it, your message will still be there, even if you have not sent it yet. 6. New sound, good idea, it is better distinguished from other messengers.
7. History-tracking, so that if users go to different talks and then click "back" button in browser they go back to previous talk, and not to previous browser page, which would usually kick them out of the Messenger (because it's a single-page-app with same URL for all states).
8. Inline playback for Audio attachments.
9. Fixes and improvements, especially in message editing and message action menu
10. Switched to FontAwesome for icons to be consistent with the rest of the site.