Changing Hidden Options with about:config

Changing Hidden Options with about:config

Firefox has a preferences editor built in, and it's accessed by typing about:config in the Location bar. Thunderbird does not have a Location bar and does not have about:config either.

Not to confuse you, but an extension named about:config does exist for Thunderbird. This extension enables you to easily modify or create new preferences.

Installing the about:config Extension

The about:config extension can be downloaded from https://addons.mozilla.org/extensions/moreinfo.php?application=thunderbird&numpg=10&id=423. It is very small, so connection speed is not important.

After the extension is downloaded, open Thunderbird's Tools, Extensions menu item and click Install. In the prompt for the extension to install, click the downloaded about:config extension's XPI file.

Modifying Preferences

On the surface, the only change about:config makes in Thunderbird is to add a menu item under Tools named about:config. Clicking this menu item displays the about:config window (see Figure 13.7). The about:config window has the capability to search for preferences and to let you edit or change any preference listed.

Figure 13.7. The filter in the about:config extension lets me see only those preferences that meet my search filter.

To add a new preference, right-click anywhere in the about:config preferences list and select New, (type) from the pop-up menu. You can also copy a preference's name or value to the Clipboard, modify the preference, and optionally reset it if the preference is not the default value.

Editing Thunderbird Configuration Files

Three configuration files are designed to be modifiable by the user. None of these files are present by default, so you must create them:

• user.js This is the first file you can create, and it's the file that's used to hold preferences that will be merged into the prefs.js file by Thunderbird. If the preference already exists in prefs.js, it is updated with the value from user.js. After they have been merged into prefs.js, user.js serves no purpose until it's modified again. If you delete user.js, the changes that were last loaded from it remain in prefs.js unless specifically removed (with either about:config, or by editing).

• userChrome.css The way that Thunderbird looks to the user can be customized in this file. It's similar to a theme, although not nearly as powerful, and you can change fonts, colors, and various other attributes for Thunderbird.

• userContent.css This file controls the way content looks in Thunderbird.

Changing Configuration Settings Manually

Manually changing configuration files can be done with a compatible plain-text editor. Rather than attempting to modify prefs.js, it is better to enter your changes in user.js.

Creating and modifying userChrome.css and userContent.css, at least initially, can be tedious. After you learn the ins and outs of Cascading Style Sheets, things get easier (refer to Chapter 6, "Power Firefox Tricks and Techniques").