This post was published 1 year, 5 months ago. Due to the rapidly evolving world of technology, some concepts may no longer be applicable.
While it is easy enough to use F12 to display Firebug in Firefox, I just like the status bar icon. Unfortunately, it has been hidden in the last few releases of Firebug. To display it, open about:config, and set extensions.firebug.showStatusIcon to true.