This modification for Firefox, created by "falconer" on Mozilla Add-ons, requires:
Camifox (https://addons.mozilla.org/en-US/firefox/addon/7527)
or Chromifox (https://addons.mozilla.org/en-US/firefox/addon/8782)
Show the Back/Forward drop-down menu on the Navigation Toolbar (so you don't have to right-click Back or Forward to show it).