Change Firefox Themes instantly with Personas
The normal way of changing Firefox themes is painfully slow. You download and install the theme from the Mozilla website and activate it afterwards. Then, after activating the theme in the Themes menu you have to restart Firefox so that the new theme will be displayed after the next start.
Personas is a Firefox extension that was developed at the Mozilla Labs. It adds an icon to the status bar that allows you to quickly select a theme which will be activated without a restart of the browser.
I would say that roughly 30 themes are available in categories like popular, sports, nature and geometric.
While this is surely a great way of enabling themes - something that Opera can do for a long time with all themes available on the Opera homepage - it has its limitations. The biggest is of course the limited number of themes that can be activated with no way of adding additional themes to Personas, and the fact that these themes can only make slight modifications to the browser UI.
Basically, all you get is a new background image that is shown in the browser's chrome, and that is about it.
This is in my opinion the biggest drawback of the add-on.Complete themes or full themes allowed for the modification of all browser UI elements; Persona only to add a new wallpaper to the browser.
Another downside is that it does seem to add quite a few Megabytes of Ram usage to Firefox.
Update: Personas has been integrated natively into the browser, which means that the add-on is no longer required to add a new basic theme to the browser.
Update 2: Personas Plus is an add-on that makes the installation of themes even easier.
Update 3: Mozilla has announced a name change for Personas, which in the near future will be known as themes, or background themes instead. The move was fueled by the announcement that Mozilla BrowserId would be renamed to Mozilla Persona.