You can use folders to add more bookmarks to the Bookmarks Toolbar. *https://support.mozilla.org/en-US/kb/bookmark-folders-organize-your-bookmarks

Thanks. This is too cumbersome. I want all toolbar bookmarks visible at the same time, without shuffling folders. There's no excuse for being unable to expand downward by dragging the lower edge.

You can use CSS code in userChrome.css to get a multi-row Bookmarks Toolbar. *https://github.com/MrOtherGuy/firefox-csshacks/blob/master/chrome/multi-row_bookmarks.css ---- More info about userChrome.css/userContent.css in case you are not familiar: *https://www.userchrome.org/what-is-userchrome-css.html *https://www.userchrome.org/how-create-userchrome-css.html *https://www.userchrome.org/firefox-changes-userchrome-css.html You need to set this pref to true in about:config to enable userChrome.css and userContent.css in Firefox 69+. *about:config => toolkit.legacyUserProfileCustomizations.stylesheets => true *https://support.mozilla.org/en-US/kb/about-config-editor-firefox