Gnome setup in Ubuntu

[Colin Law]

Hi

I have previously added the Gnome desktop to a standard Ubuntu install by
sudo apt install ubuntu-gnome-desktop^
I find I can then install shell extensions by opening Gnome Software
and clicking on the Add-ons button.

On a new system, however, I installed Ubuntu Gnome (17.04) directly
and when I open Gnome Software the Add-ons button is missing.  Google
has failed to help me.  Does anyone know how to get the Add-ons
button?

Colin