One of the thing that's extremely unhandy when you are working with Firefox preferences is that you cannot access a detailed explanation of a preference's functionality directly. You have to copy the name, do a search on the web in hope of finding a suitable explanation. This often leads to the Mozillazine entry of the preference, but sometimes to no explanation at all.
The brand new Firefox add-on What's That Preference closes this gap, by linking preferences of the web browser to entries at Mozillazine. It should be noted that the site does not cover all Firefox preferences, but for those that it does, it is usually the best source of information.
The extension adds an entry to the right-click context menu in the advanced Firefox configuration listing. You can open that page by entering about:config in the Firefox address bar to load the preference listing. First time users need to confirm the warning message before they can start making changes to the configuration.
Just right-click a preference and select the MozillaZine reference link that is displayed in the context menu. This opens the corresponding MozillaZine page in a new tab in Firefox.
You find detailed information about the selected parameter if the entry exists on MozillaZine, which it does for most of the standard preferences available under about:config.
What's That Preference is a handy extension for users who make changes regularly to the advanced preferences of the web browser. It can save lots of web searching for preference definitions.
The extension is available for all versions of Firefox 4 and newer. It can be directly installed over at the official Mozilla Firefox add-on repository.