[vinceleers]

Thanks Maurice, I think you got it right... I didn't have the patience to try to fully understand the feature. But now it seems so obvious to me!
My own approach was always to create a new workspace by clicking the plus button after I did something specific. By that I wanted to save the current workspace under a new name. But the trick is to create a new workspace before browsing on a new subject and to name it after that new subject.

I've been using Workspaces for quite awhile. I have about 25 of them, each one with a unique set of tabs with related sites. One of them, my default, I named "Default" and I do most of my basic work in that Workspace. If I end up with several tabs that are related somehow, I'll either Show Workspaces and rename my "Default" with an appropriate subject name and then create a new "Default" OR create a new empty Workspace, name it appropriately, make sure it's the current Workspace and then with the old "Default" Workspace selected on the left, drag the links on the right into the tab bar of the new Workspace's window. All this done in the Show Workplaces window.