Q:

Facebook Messenger app/notifications on Linux 2019? 

Searching only brings up old results from around 2013 or 2014.  How is the state of things for Facebook notifications on Linux?  Is there an app that notifies me when new messages arrive?  Any kind of notification is welcomed, if not sound at least a flashing light on the panel bar, anything. ( Xubuntu 16.04.3 here)

A:

There is an app called Caprine which can be used as Facebook  messenger.  The software offers .deb, .snap, and .Appimage packages to make it easy to install. 
According to their github page

Desktop notifications
Desktop notifications can be turned on in Preferences.