Add-ons using the techniques described in this document are considered a legacy technology in Firefox. Don't use these techniques to develop new add-ons. Use WebExtensions instead. If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions.
Starting from Firefox 53, no new legacy add-ons will be accepted on addons.mozilla.org (AMO) for desktop Firefox and Firefox for Android.
Starting from Firefox 57, WebExtensions will be the only supported extension type. Desktop Firefox and Firefox for Android will not load other extension types.
Even before Firefox 57, changes coming up in the Firefox platform will break many legacy extensions. These changes include multiprocess Firefox (e10s), sandboxing, and multiple content processes. Legacy extensions that are affected by these changes should migrate to WebExtensions if they can. See the "Compatibility Milestones" document for more information.
A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.
Obsolete since Gecko 35 (Firefox 35 / Thunderbird 35 / SeaMonkey 2.32)
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
Create a page that does not contain navigational elements.
Usage
With the Add-on SDK you can present information to the user, such as a guide to using your add-on, in a browser tab. You can supply the content in an HTML file in your add-on's "data" directory.
Note: This module has no effect on Fennec.
For pages like this, navigational elements such as the Awesome Bar, Search Bar, or Bookmarks Toolbar are not usually relevant and distract from the content you are presenting. The addon-page module provides a simple way to have a page which excludes these elements.
To use the module import it using require(). After this, the page loaded from "data/index.html" will not contain navigational elements:
var addontab = require("sdk/addon-page");
var data = require("sdk/self").data;
require("sdk/tabs").open(data.url("index.html"));
This only affects the page at "data/index.html": all other pages are displayed normally.