Mozilla Cautions Against Experimental Firefox Plug-Ins

Firefox add-ons allow users to personalize their browsing and add additional features, and because Firefox is open source , many of these add-ons are thought up by third-party developers.

Add-ons classed as "experimental" are those still being tested, although they are available for public use.

However, Mozilla does not recommend users downloading such add-ons unless they are very technically minded.

"They haven't been approved and so they may pose risks to users," said a company spokesperson.

Behind the Great Firewall

The China Channel experiment received international press coverage on its launch because it allows users to surf the Web as if they were in China.

The press coverage came at a time when Internet censoring in certain countries was attracting increased consideration from human rights groups and multinationals, essentially culminating in the launch of the Global Network Initiative -- a statement by a large number of organizations, including Google (Nasdaq: GOOG) , Yahoo (Nasdaq: YHOO) and Microsoft (Nasdaq: MSFT) , to stand up against government policies that curb freedom of expression on the Internet.

More than 1,000 Firefox users downloaded the China Channel. It does not appear at first glance to be problematic.

"It's open source, free and easy," reads the add-on's landing page. "Take an unforgettable virtual trip to China and experience the technical expertise of the Chinese Ministry of Information Industry," it says.

Browser Went to China, Never Came Back

However, when vnunet.com tested out the add-on, the pages the China Channel is there to restrict seem to be lost for good, even when the add-on is disabled.

Other testers appear to also have had problems -- one user who commented on the China Channel's site said he had experienced an "uninstall bug." All proxy settings were lost after he closed Firefox, he said.

Mozilla points frustrated users to small print loosely attached to add-ons.

When users are given a choice to login to install an add-on, they can click on a "why?" button. If they do so, they get the following information:

"This add on is meant for advanced users to test add-ons before they are made available and reviewed for general use. Many add-ons may be in prototype form. Experimental add-ons may be alpha, beta or pre-production in quality, performance and features. Caution should be used when installing experimental add-ons, as they have not been tested by an editor and may harm your computer configuration."

The Firefox UK marketing team said it was unaware the add-on had received widespread press coverage and plans to investigate how a potentially dangerous application is quickly becoming a popular experiment.

In related news, Mozilla launched its China edition of Firefox Tuesday.