.json files are bookmark backups and must be restored not imported.

See http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox and note the differences between "backup & restore" and "export & import".

Menu changes (wording), "Organize Bookmarks" under the Bookmarks menu has been changed to "Show All Bookmarks -- Ctrl+Shift+B" with the same keyboard shortcut. They didn't like the new wording either and it is expected to be changed in a later version.

You can make Firefox 4.0.1 look like Firefox 3.6.17, see numbered items 1-10 in the following topic Fix Firefox 4.0 toolbar user interface, problems (Make Firefox 4.0 look like 3.6)

Well, I'm very familiar with how to restore a json file. My point is that on the library screen, there is no backup and restore button. I know exactly what you're referring to and it isnt there. I'm using Ubuntu's Firefox 4.0 if that helps.

I see you have nothing in the Library toolbar to do anything, that would be a bug, not a usage problem. What happens if you use Help > "Restart with add-on disabled" does the problem go away (Safe Mode - one time) that would implicate an extension or theme, or maybe Ubuntu as you mentioned. Would be hard to believe that would have been missed in beta testing.

If it looks bad in Safe Mode as well then, it would be important to get it tested in Aurora (currently 5.0a2 if it still means anything) as Firefox 5.0 will be out soon. Can you test Aurora on your system.

Actually the current version of Firefox is 4.0.1 not 4.0 try updating through Help > About Firefox

I'm no good a searching for things in Bugzilla.

If it helps you the keyboard shortcuts within the Library List are

Alt+O    Organize
Alt+V    Views
Alt+I    Import and Backup

anything else was added by an extension and has no keyboard shortcut.

Would be nice to know if that works even when you can't see the Library's toolbar dropdowns but would see the dropdown once the shortcut is entered and be able to continue.

I think you got it!

On Ubuntu (at least) the options "Organize", "Show" and "Import and Backup" are hidden on top of the screen, not on the window bar. You have to open the "Favorites">"Show All" and hover the bar on the top of the screen, the one with the Ubuntu logo ont the left.