All About about:config

Most people already know about about:config but I thought I'd mention it anyway, just as a token of appreciation to the the fact that Firefox lets customize it to do things exactly the way you want them to be done, which makes it all the more a wonderful application to use.
All you have to do is type in the words about:config into the URL bar and hit Enter. You might receive a warning that looks something like:


That warning isn't there for no reason, and most people will advise you not to mess with things that don't make obvious sense, so better be careful. However, once you do click on the button, you will see a screen that looks like:


This page is basically a list of preferences (a huge list at that, but, it's not complete, there are lots of other preferences not shown in this list). There's a column for the preference name, which apart from uniquely identifying the preference, also gives you an idea about what it's for (in most cases). If you paln on designing an add-on which depends on one of these preferences, the preference name is what you should be using. More on handling preferences here.

Next, there's column showing the status, whether a preference currently bears it default value, or one set by the user. Preferences set by the user are shown in bold. The term user set doesn't really mean the preference has been set by the user herself, it could have been done by an extension, or a theme, or an external application. So you might want to think twice before you decide to restore defaults.

Then there's a column showing the preference type:string, integer or boolean. The next column shows the value currently held by the preference. You can change the value of a preference by double-clicking on it. If the preference is a boolean, it is toggled automatically, otherwise you are prompted to enter a new value (in case of integers and strings). You can also add new preferences by right-clicking, and selecting New.

There's also a search box(at the top of the page, in case you didn't notice) that allows you to filter preferences that contain the string you enter in the box. This, plus the fact the preferences are extremely well-named, make this page extremely easy to use. For example, you can simply type in tab to see and modify almost all the preferences related to tabs.

If there's something you feel can be done differently, without changing the structure of firefox itself, then you will, in most cases, find a preference that lets you do that. I, for example don't like the downloads window popping up when I start a new download. If you type in download in the filter box, you will find a series of preferences beginning with browser.download.manager that let you control certain properties of downloads window. In my case, all I had to do was double-click on the preference browser.download.manager.showWhenStarting which is a boolean set to true by default, and is responsible for opening the downloads window when a new download starts. You might find some interesting preferences under the keywords: mouse, history, bookmark, extension, url, cache etc.

One must, of course, be extremely careful while changing preferences, for, as the warning indicates, changing them can be harmful to the stability, security, and performance of Firefox. Do so, only if you are sure of what you are doing. It is a good idea to verify what you plan to do, before actually doing it.