With this add-on you have available in a toolbar button a menu with your Bookmarks Toolbar items or alternative a custom search results items, so you can save space by hiding the "Bookmarks Toolbar".
After installation and on first Firefox restart you will be confirmed in order for the button to be added in toolbar. (or you can add it manually with right click on toolbar, select 'customize' ).
"Bookmarks menu" will be available in Toolbar Context Menu when you install it.
It will monitor any changes you'll make in "Bookmarks toolbar", so adding a bookmark or organizing your bookmarks you'll see the changes in the add-on immediately.
Highly recommended in combination with Personal Menu add-on: https://addons.mozilla.org/en-US/firefox/addon/3895/
which inspired me to create this add-on.