Smart approach in tiny addon Noté 5 sur 5 étoiles
But this approach with small improvements can make a revolution in web browsing.
Let imagine that similar trobbering is applied to every Bookmark folder.
What can we do with these folders now?
Left click gives us list of bookmarks/inner folders and right click - bookmark context menu.
But we have also left double click, right double click, middle click and Alt+(all kinds of clicks).
In other words we can call without opening folder's list 8 bookmarks per folder!
And if we could distinguish short click from long click (like on back-forward navigation arrows) we can cancel Alt-accompany (it is less comfotable).
Moreover, we don't need assign addresses - the bookmarks themseves contain them and, let say, 5-8 top bookmarks of each folder can be called by this way.
The property of each bookmark defines - to open it in sidebar or in tab and new tab or current tab is common for all bookmarks.
I think, such implementation will be even simpler. And it can be another addon.