18.04:LTS, GNOME new browser tab with mouse middle button click?

[mgeo03]

I've just done a clean install of 18.04LTS on a Dell E6530 laptop. I'm used to using a middle mouse button click in browser (Firefox or Chrome) window to open links in a new tab. On 18.04 this opens the Activities Overview view. I'd like to disable this default behavior and use the middle click to open links in a new tab. I've done this already on 18.04 but lost my notes on how it was done

I seem to recall it was a setting I reached in dconf-Editor but I'm having trouble finding it.

Any help would be greatly appreciated.

Thanks,
George