Top 10 Firefox extensions to avoid

Tabbrowser Preferences

This extension lets you tweak Firefox's tab settings in various minor ways. For instance, you can add a New Tab button to your tab bar, or control whether the Close Tab icon appears on each tab or at the end of the tab bar. It works fine.

The problem is that if you uninstall the extension, it doesn't reset your tab settings, leaving you with tweaks that you have to undo by going to the about:config page, which many users don't understand or even know about.

If you uninstall this extension, you'll have to delve into the about:config page to undo the changes it made. That's poor extension etiquette.

The changes the extension makes are fairly subtle, but that's not the point. If you uninstall an extension, you do so for a reason, and once it's uninstalled, the browser should be reset to its default state.

Tabbrowser Extensions

This extension is a real heavyweight but seems quite popular in certain Firefox circles -- it almost seems to be a rite of passage for Firefox nerds. It gives you lots of control over how tabbed browsing works and even supports plug-ins to add even more functionality. However, it is buggy and conflicts with many other extensions. In fact, even its developers suggest that you not install it!

When the people writing the code suggest you stay away, you should stay away, no matter what your über-Firefox-geek friend says. In any event, the extension hasn't been -- and probably won't be -- upgraded to support Firefox 2.x.

Bonus: Watch out for the Numbered Links 0.9 imposter

There's nothing wrong with the Numbered Links 0.9 extension per se. By showing numbers next to links, buttons and other interactive elements on Web pages, it lets you navigate without using a mouse. If you chose to install Numbered Links 0.9 previously, there's no reason not to go on using it if you find it helpful (though you might be interested in Conkeror by the same developer).

However, if you see this extension in your add-ons list and don't recall installing it, then tread carefully. There's a version that has been modified into the FormSpy Trojan, which installs itself as a Firefox extension and keeps the title "Numbered Links 0.9." FormSpy can potentially capture information entered into HTML forms and send them on to a malicious Web site. For more information, see McAfee's FormSpy profile.

What do you think?

So there you have it -- our 10 picks for Firefox extensions to avoid, plus an imposter to really be on the alert for.

As always, we welcome your thoughts. Have any extension horror stories you'd care to share? Want to defend an extension that we've listed? Please use the comment form at the bottom of the page.

Peter Smith is a Web developer and freelance writer with a special interest in personal technology and digital entertainment.

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• Preston Gralla: Why Firefox has lost its mojo
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• Martin McKeay: Firefox and irresponsible disclosure
• Daily IT Blogwatch: It's IE8 vs. Firefox 4 for 2008 (and animal noises)
• Scot Finnie: The Great Mac Software Hunt
• Firefox loses browser share, Safari gains

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