With this extension, Lightweight Themes (formerly, "Personas") are limited to unselected tabs and the empty space around them. It also allows the user to define the amount of padding around the tab bar to control how much of their theme is uncovered (default: no extra padding). It can also be useful for podcasters and video producers who want a branded web browser to display on live streams or televised video.
See a quick walkthrough on YouTube: http://youtu.be/qEN90LaVrXA
See its source on GitHub: https://github.com/ScottMichaud/LighterWTAustralis
See my portfolio website: http://www.scott-michaud.com/
Note: The two Lightweight Themes used in the example screenshots are
1) Furfox Tail Twister: https://addons.mozilla.org/en-US/firefox/addon/furfox-tail-twister/
2) Binary: https://addons.mozilla.org/en-US/firefox/addon/binary/?src=ss
... and are the creations of their respective authors.