New tab, new tab, new tab!!!
YEEEHA!!! 
Thank you, thanks, danke, gracias !!
I love you !
My mice do not have a middle click button, only a wheel button and yeah, that’s not intuitive or comfortable to use. The only time I do use it is on the very rare occasion I see any value in slowly auto-scrolling a web page. Otherwise it is not a button, it is a wheel.
There is simply nothing like the default action doing what I expect it to.
Keyboard shortcuts may be handy for some people but for me are useless in the Firefox Sidebar context because the sidebar is in a different focus context. I never use the keyboard in Sage-Like. I never use keyboard plus mouse shortcuts at all actually. Anywhere in any app. Unsure why other than maybe it is just harder to co-ordinate and less efficient.
Recently I changed the default Firefox context menu (outside Sage-Like) to always - or often - show Inspect Element (Q) at the top as this is the primary, almost only, context menu option I use. Reload? F5 or nav bar button. Cache-bypass reload? Ctrl + F5; Fwd / back? Backspace is the most efficient (which Firefox is annoying preferencing off) or just navigation bar buttons. Etc etc.
Yet, after over a decade of right-clicking on thousands of element, moving the mouse all the way to the bottom and clicking, having made this change, guess what? I am struggling to get out of the habit! More tellingly perhaps, I know I can right-click then hit Q to get there faster. But it is just not that simple to change behaviour!
Speaking of which, Sage opened articles in new tabs for so long, I became familiar with it. Or Sage at inconsistently allowed the overall browser setting to permeate through to itself, that I ‘learned’ that behaviour as well So when Sage-Like finally came along thanks to your excellent efforts, to replace Sage in the WE era, it was enormously welcome … except … this, one, little - but massive - thing! Hahaha.
Now, all is right with this bizarre world again. The change to Quantum and WE all but finally complete thanks to your update!
I guess if I was a pianist, using three mouse buttons might be more natural.
Glad you were able to keep the option for new or existing tab override with middle and keyboard override if that is what you like.
For me, everything is opened in a new tab. That way I never feel like there is a long train of history hiding where I was and confusing my mental mind’s eye about where some site, that I still visually remember, has gone. Searches; omnibox activity; bookmarks; link sent to Firefox for opening … it is all opening a new tab. If I close a tab and need it again, that is what Undo Close Tab is for
Thanks so very much for this effort. I know it may not make a lot of sense to you as we all tend to default to only really ‘believing’ our way is the norm. That is just an instinctive thing. I am the same even though I know people use software in a variety of ways that are different to mine. But this change makes Sage-Like the perfect replacement / successor to Sage, for me.
Also, have been using the address-bar feed addition button more lately. Think it was hidden by my custom CSS until now. Very helpful.
Last but not least, have been cleaning up my bookmarks and that meant yet another naming scheme including renaming the Sage-Like feeds folder. No idea how … but unlike in the past with original Sage, the renaming did not cause any issue! Sage-Like just automatically picked up the new folder!!!
Brilliant
That makes Sage-Like actually superior to Sage, for me.
