Created attachment 730662 [details] Only emit a popup when new items show up It seems that liferea's behaviour, when "Show a popup window with new headlines" is enabled is to display a new popup, each time a feed that contains unread items is refreshed. There's no memory that a new/unread item already generated a notification in the previous refresh cycle. I think the correct behaviour would be to issue a popup notification, when an item is really new, not when it is unread. Possible fix is attached.
Given that this problem isn't packaging-related, this has been submitted upstream: https://sourceforge.net/p/liferea/bugs/1110/ Closing with the UPSTREAM resolution.