Mozilla on Friday said that it has added the Skype Toolbar to the Firefox Blocklist because the browser extension is buggy.
Users who have installed the Skype Toolbar will be notified that the toolbar has been disabled and presented with the option to re-enable it. But that probably wouldn't be a good idea.
The Skype Toolbar, said AMO, Mozilla's add-on management group, was responsible for over 40,000 Firefox crashes last week and was one of the "top crashers" of Firefox 3.6.13. And beyond that instability, AMO claims that the Skype Toolbar uses inefficient code that can slow Web page rendering by a factor of 300.
"We believe that both of these items constitute a major, user-facing issue, and meet our established criteria for blocklisting an add-on," said AMO in a blog post.
The Skype Toolbar extension for Firefox is bundled with Skype's desktop application, so users of Skype's desktop software may have installed the toolbar without being aware of it. In the past, this was an issue: In 2008, if not more recently, Skype's installer software did not notify users during upgrades that the toolbar extension was being installed, a fact that annoyed some users.
AMO said that it has contacted the Skype Toolbar team and is working to resolve the issue. When that happens, the software will be removed from the blocklist.
In July, AMO identified a malicious add-on, "Mozilla Sniffer," that had been blocklisted, along with an add-on called CoolPreviews that contained a significant vulnerability. The group made a similar announcement in last February, when it identified two malicious add-ons.