Draft: Show notification and play sound for new messages on Linux
Still WIP since missing libnotify or even notification server is not tested nor handled appropriately yet: As per #156 (comment 67055) we want to inform the user that they should install libnotify for notifications to work.
- current "new" message count does not include unread messages at application start, but still decrements if those are read. We could discuss if we wanted to change wording from "new" to "unread" and include those as well (related to #133 to get a sum for all private messages)
- on Android, despite saying "x new private messages", the implementation is actually counting the number of contacts with unread messages. We should decide which way makes more sense. We could also add more information and say "x new messages in y private chats"?
- needs to be tested with different notification servers (see the list here)
Successfully tested on Debian/Xfce with xfce4-notifyd and libnotify installed: