This is a modified version of my
Mile Wide Back extension that uses the Firefox Sidebar to navigate the current webpage.
The advantage is that with the Sidebar always visible, users can navigate their browser tabs even when the active webpage is still loading.
Otherwise all the features and behaviors are the same as my
Mile Wide Back extension.
For additional customization, you can modify Firefox's
userChrome.css file to make the sidebar narrower by adding this CSS code to your
userChrome.css file. You will also need to enable "
toolkit.legacyUserProfileCustomizations.stylesheets" in the
about:config setting too:
#sidebar {min-width: 0 !important}
