@zalex108 I've been now testing
Group Your Tabs, but it isn't quite what I was looking for. See, I do have many tabs open, but usually they are from various different websites and domains; the only thing in common is the theme. For example, when you are making Google searches and you right click many prominent websites open into a new tab, that's the kind of organizing / grouping I need in my work - and a lot.
Even an empty tab in all it's simplicity would serve my needs perfectly! But Opera has changed empty tabs to Speed dial, and everytime I boot my system, the Speed dial tabs close