I was missing this desperately after Mozilla decided to cripple the most valuable Addons like "GoToParentFolder" and others. Thanks a lot.

so far soo good

При открытии двух папок закладок, прокручивая вниз текст накладывается на текст.

Parfait ,merci

Required add-on but needs further work
1) Clicking on the "bookmark manager" button results in an error - "Illegal URL: chrome://bookmarks/"
2) The search is not working well, there are a lot of links in the results that do not contain a search string in either Title or Address.
Perhaps you should do a search by Title and by Address separately.
Those. make a search option with a choice - either by title or/and by Address

It Works! But UI can be improved!
ex. use dedicate bookmark/folder icon when icon can't be retrieved

Noooo... To get icons, It refreshes all my bookmarks with bookmarks as login on some online services so now all these accounts have updated last seen time...
Future of FF with Webextensions isn't clear if addons do what they want and can't be controlled by user not vice-versa...

So addon is helpful to locate a bookmark folder, to find folder that contains an specific bookmark

When I click addon button it opens a small, compact window of it's own, how to make that open in a tab instead?

This extension does work as description said. But, it noticeable slow when loading its view. In my system it actually need 2 seconds to load top tree. More if I open the main tree.
Probably because I have 2000+ bookmarks and multi layers folders.