gnome-session-flashback 1:3.26.0-1ubuntu1 (amd64 binary) in ubuntu bionic

 The GNOME Session Manager is in charge of starting the core components
 of the GNOME desktop, and applications that should be launched at
 login time. It also features a way to save and restore currently
 running applications.
 .
 This package contains the required components for the GNOME Flashback
 session, based on GNOME Panel 3. It can be started from a display
 manager such as GDM, and doesn’t have specific hardware requirements.