I had an offline talk with Yana and she told me to ask you about this.
Currently when you close a multichat window you leave the room.
This was not the case before with IRC. When you close the window wou can still receive messages and stay online on IRC channel, even more as IRC channels are persistent when I start sip-communicator I'm not automatically joined in last channels on which I was online because their windows were closed and channels were left the last time I stopped the application.
Yana suggested to check whether the channel is persistent and if it is do not leave the room on closing and leaving otherwise.
What do you think about this?