Thank you!
This chat component will have a great development in next months with a lot of new features.
As for now, the conversations as kept using Joomla sessions, so when you close a chatbox and reopen it, the comversations are not lost. The conversations are lost when you logout and Joomla session is lost.
As a priority requirement, in next release 2.3 is already planned to develop a messages history system, to allow to recover previous conversations when you logout and login again.
About the offline users currently is not supported, but it's a good feature request so i'll add to wishlist to develop
Thanks for all
John