I have a multi-monitor (two) setup and I'd like to be able to see all the windows I have open when I switch between workspaces. At the moment I end up overlooking that I already have a window open somewhere because the thumbnails only include the windows from the primary monitor.
I've already used the Tweaks tool to configure the workspaces to span displays, so I do have separate windows on each workspace, it's just that they aren't easily shown.
I've had a look on https://extensions.gnome.org/ and I don't see any extensions there which would do this.
In case it matters I'm also using the Dash to Panel and Workspace Matrix extensions (so it's actually the thumbnails in Workspace Matrix I care about, though I'm assuming that it's Gnome itself which is generating the thumbnails).