The embedded Sametime client in the Notes Client opens every time in one window with all lapsed chats.
If you got, lets say "some" associates withing a 1.500 users company, the list of lapsed chat grows fast. within a day the list is longer as the window may cover it.
Any morning this list will be provided with all the persistent chats from the Mongo DB until the first loading issues becomes visible.
This missing clean up already leads into errors.
This list never gets cleaned up. Only if the user takes some time an closes the chats, one by one.
Closing the window does only pause the chats.
But - hey - there is a "Close all" option at the tiny gear menu right hand.
But sadly, it does simply the same as the "X" at the window. It only pauses the situation. "Close all" does just hide the window. It closes no session, no chat.
I like to propose a police driven setting
This controls the re-open behaviour after a close by "X", ESC, or a close menu action: Close all chats and start from new with non of the lapsed chats
or - switch to the currently existing behaviour. (non default) If this behaviour is chosen, a "real" close all chats action should also be available in the menu.
The issue is already addressed by case CS0147504 and SAME-35813.