Room setup in Openfire + Spark

Worth OpenFire 4.4.4 on Windows Server 2018
As a client, Spark 2.8.3 is used.
Server room created.
The problem is that if you close the chat window in Spark with a cross, you exit the room, to read the conversation you need to authenticate again and open the chat window.
How to make sure that the user once entering the room is constantly in it?
Perhaps there is some kind of plugin for OpenFire.

There is no plugin. This is how group chat works in XMPP in general, which is Openfire and Spark are based on.