Currently, Teams has no way to close a chat window in the traditional manner (for example as in SfB clients)
Now Teams appears to be gaining this feature as part of Multi-Window Chat Featured ID: 57292 https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=57292
This allows a user to at least undock a chat, and even get appearance of the chat as a separate application window in the windows task bar. As a consequence, the traditional X to close chat window option now is available (at least it undocks the popout chat window back to Team client)
Question: How can a bot developer or remote parties get any indication that the user has closed (X'ed the chat) window? This could be by means of an event in the bot framework or a call back from Graph for example.
This is needed for certain contact center applications where it is important to know that the user has "left" the chat.