Double-clicking on a chat in the list opens it in an additional window that only contains the chat itself.
In this way it would be possible to display several conversations at the same time.
Actual behavior
It is not possible to see more than one chat at a time.
Explanation
Sometimes you chat with several people independently at the same time.
I think that it would be useful to be able to see all chats at once.
Unlike old messengers, most modern ones lack such a feature.
The only exception I’m aware of is iMessage.
indeed for desktop it makes sense to be able to open a chat in a new window so you could see more than one chat, for example, right-clicking the chat in the chat list to open the menu and an option “open in a new window” could exist
there is no point in Tabs, because indeed that is how it currently works, the chat-list is nothing more than a vertical tab panel and when you select a chat you focus that tab
(that is in practical terms, not saying that the actual implementation is a tab panel)
gmail has a multiple inbox feature. maybe this gmail feature is applicable to this use case. when you want to write in multiple chat types at the same time
example
instead of tabs, a vertical list of inboxes appears.