This add-on has been discontinued.
For me it became impossible to keep up with the constant changes that are introduced with each new version of Firefox.
All functions of this add-on can be found in Classic Theme Restorer:https://addons.mozilla.org/en-us/firefox/addon/classicthemerestorer/
Puts back the favicon in the URL Bar.
Replaces the horrible default favicon (empty dotted square) with a nice classic generic favicon.
Restores a style similar to Firefox 3.6 in showing the verified domain and verified identity.
Optionally doesn't show the Tab Bar when only one tab is open (addon preferences).