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Part VI — Creating Extensions and Themes After the extension is installed, it is visible in the Extensions dialog. You can use this dialog to get some information about the installed extensions, their version number, author, home page, and so on. Some extensions implement an Options dialog that can be used to configure the extensions. This dialog is also accessible from the Extensions dialog. Firefox has an update mechanism that allows new extension versions to be automatically downloaded and installed when they are available. An extension can specify a URL of a configuration file with information about the latest available version of the extension. Firefox periodically queries this file and sees whether a new extension version is available. If it finds a new version, it displays a dialog that informs the user about the new version. If the user decides to update the extension, Firefox automatically downloads and installs the new version. If an extension doesn’t specify a custom update file URL, Firefox tries to query the Mozilla Update site for a new version of the extension. You can manually check whether a new extension version is available by opening the extension context menu in the Extensions dialog and choosing Update.
When you no longer need an extension, you can either disable it or completely uninstall it from your browser. Both operations can be performed in the Extensions dialog. When an extension is uninstalled, it is first unregistered from the various browser configuration files, and then its files are removed. The next chapter provides further details about the Extensions dialog, the structure of an extension package, and other extension-related Mozilla mechanisms.
Summary This chapter provided an overview of the main Mozilla technologies and explored the possibilities of Firefox extension programming. Get ready to dive deeper into the process of creating Firefox extensions in the next chapter.