Opera Software says Microsoft's 'kill switch' for Internet Explorer 8 (IE8) isn't enough to solve its newest antitrust problems with European Union regulators.

"That's one possible step," said Jon von Tetzchner, the CEO of Opera Software . "But it doesn't really change much, does it?"

A December 2007 complaint submitted by Opera to the European Commission prompted the antitrust agency to charge Microsoft in January 2009 with stifling competition by bundling its browser with Windows. Specifically, the commission said that Microsoft "shields" IE from competition by distributing the application with its operating system.

Two weeks ago, when Microsoft confirmed that it would allow users of the upcoming Windows 7 to block IE from loading, some, including von Tetzchner, speculated that the option was prompted by the recent antitrust action.

"I would not be surprised if it was linked [to the charges]," he said.

Microsoft has declined to comment on whether the decision was connected to the Commission's move.

Although the Commission has not spelled out what it might demand of Microsoft if its charges stick, it has hinted that the company might be forced to disable certain portions of IE and/or offer users the choice of other browsers.

"The important thing would be consumer choice," said von Tetzchner. "The quick answer would be to offer other browsers. How exactly that would be done tactically isn't up to us, but consumers should have an equal choice of browsers."

"The internet was founded on choice and openness and this requires a level playing field with multiple options for accessing it," said a spokesman for Google, which recently joined Mozilla and Opera in the case against Microsoft.

"From the moment a computer is turned on, people should be able to access a range of browsers easily and quickly."

Mozilla, the developer of Firefox, refused to comment when asked its position on the IE8 'kill switch' in Windows 7.

"The important thing is to make sure that the web stays open and there is a choice," said Opera's von Tetzchner. "We haven't ensured that we won't lose competition in browsers, and that's something worth fighting for."

Last week, the EU extended Microsoft's deadline to reply to the charges over IE until April 21.

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See also: Mozilla joins EC in Microsoft anti-trust case