I can verify that the proposed package in the link
https://launchpad.net/ubuntu/+source/gnome-flashback/3.28.0-1ubuntu1.4
did work for me.
I can verify that the proposed package in the link
https:/ /launchpad. net/ubuntu/ +source/ gnome-flashback /3.28.0- 1ubuntu1. 4
did work for me.