Chat list can be accessed from left menu
It can also be reached by clicking on dashboard widget titles.
If you want to allow operator to list all chats by department grant him
if you want to limit that grant him only
'lhchat','list_my_chats' also you can additionally grant
If you want to grant operator to list all chats independently of chat owner status
Allow operator to list all chats independently of operator and status.
If you want to allow operator to list only chats he is owner
Allow operator to list chats he is owner
Also if you want to allow hom to list pending chats without a chat owner grant him
Allow operator to list chats without an owner and in status pending.
Permissions for chat opening is explained here