Modify and extend Mozilla applications Add-ons add new functionality to Gecko-based applications such as Firefox, SeaMonkey, and Thunderbird.
There are two main types of add-on: Extensions add new features to the application, while Themes modify the application's user interface. For both extensions and themes, Mozilla operates a repository at addons.mozilla.org, also known as AMO. When you submit add-ons to AMO they are reviewed, and after passing review they are made available to users. You don't have to submit add-ons to AMO, but if you do, users can take confidence in the fact that they have been reviewed, and you can benefit from AMO's visibility as a source for useful add-ons. Add-ons can greatly affect the behavior of the application that hosts them.
Why doesn't my script run properly? Or. Building an Extension. Introduction This tutorial will take you through the steps required to build a very basic extension - one which adds a status bar panel to the Firefox browser containing the text "Hello, World!
". Note: The extension created by this tutorial won't work in Firefox versions that don't have a static status bar (that is, Firefox 4 and up). You can find a more up-to-date tutorial in the XUL School tutorial The Essentials of an Extension. Since Firefox 4 (and other Mozilla 2 based applications) there are two types of extensions: Traditional, classic, or XUL extensions are more powerful, but more complicated to build and require a restart to install.
This article explains how to build a traditional extension for Firefox. For a tutorial on building an extension for Thunderbird, see Building a Thunderbird extension. Quick Start A Hello World extension similar to what you can generate with the Extension Wizard is explained line-by-line in another tutorial from MozillaZine Knowledge Base.
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