With our borderless design, people can have conversations with your team on your website and web apps without needing to open the full Messenger:
Borderless conversations appear on the desktop web Messenger when you send chat full messages, and for all the conversation replies your teammates send.
Note: When a user closes a borderless conversation, it returns to borderless again only when a teammate replies.
Can an end user trigger it?
No, borderless conversations only trigger from teammate messages.