XUL Applications
While XUL serves primarily for constructing Mozilla applications and their extensions, it may also feature in Web applications transferred over HTTP. The Mozilla Amazon Browser, a former XUL application of this type, provided a rich interface for searching books at Amazon.com.
However, many of the powerful features of Mozilla (such as privileged XPCOM objects) remain unavailable to unprivileged XUL documents unless the script has a digital signature, and unless the user obtains grants of certain privileges to the application. Such documents also suffer from various limitations of the browser, including the inability to load remote XUL, DTD, and RDF documents.
As Gecko provides the only full implementation of XUL, such applications remain inaccessible to users of browsers not based on Mozilla. Mozilla-programmers sometimes refer to XUL applications running locally as chrome.
Other applications using XUL include:
- The Ample SDK open-source GUI framework provides a cross-browser implementation of XUL in JavaScript.
- The ActiveState Komodo IDE uses XUL as well as the Open Komodo project announced in 2007.
- The Songbird music-player and Miro video-player both use built-in XUL.
- The Elixon WCMS/XUL Content management system uses exclusively remote XUL, thus overcoming some of the aforementioned limits of remote unprivileged XUL documents.
- The developers of the Celtx media pre-production application used XUL.
- The Flickr Uploadr was built using XUL.
With the release of Firefox 4, support for remote XUL was disabled by default, due to security concerns. Loading an XUL page via HTTP would now display an error unless the domain was added to a hidden whitelist.
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