Thank you Gomita and good people at Mozilla!
Every person that uses a rectangular widescreen(16:9 aspect ratio) monitor, would most certainly find very useful to have its Bookmark Toolbar vertically(left or right side of the screen) and not horizontally(like it is in the default FF).
On these wide screens monitors, we have much more space on the left and right than on the top or bottom of the screen. So it makes perfect sense to have a vertical toolbar, because an horizontal one would take from the vertical space of the screen.
I have a vertical toolbar on FF displayed all the time, on which I have 2 very important things:
1). Bookmarks Sidebar(which I use 99.9% of the time and I access Bookmarks from the Menu only 1%)
2). Bookmarks Toolbar (where I keep at handy the most used links.
Unfortunately, to this day(2018, november) I have no knowledge of a vertical toolbar that works with the latest Firefox versions. Please say someone if you know of any such vertical toolbar that works with FF after v57.
Do to limitations in the provided APIs in Firefox 57, a lot of highly efficient and practical add-ons cannot be implemented as a WebExtension add-ons and will not work in Firefox 57 or higher.
The change from the other add-on infrastructure was done too quickly and brutally. Would it have been too much for add-ons devs, to have a tool which translated their add-on from previous technology to current?
Who is the main beneficiary(at least until now) of this mess? :::::: G O O G L E .
Check out the usage share of browsers in the last years: https://en.wikipedia.org/wiki/Usage_share_of_web_browsers
A lot of users were lured from google search page to install their browser, and the majority of users do not understand what google is.
Google represents: Spying, Monopoly, Closed and Proprietary source code which cannot be reviewed by anyone except some people at google, and little regard for customization. Mozilla is (or at least was before FF57) the opposite.
Who are the main disadvantaged people? ::: a lot of the every day users of Firefox. Since the change(after FF57), about 5% of the users have completely left Firefox, and a lot others have stopped updating beyond FF 56.