When I was running mate on another computer, I would log off or shutdown, and power up and login again and mate would restore all the gui apps in all the workspaces.
Gnome does not do that.
Also, I do not have a way to upgrade to Centos 7 because
1. graphic installation fails (as I have posted here before).
2. I do not want to do text install because it will clobber my existing partitioning scheme and does not provide for modifying the automatic partitioning scheme.