Norwegian browser maker Opera Software ASA has complained to the European Commission that Microsoft is abusing its dominant position by tying its Internet Explorer browser to the Windows operating system and hindering interoperability by not following accepted Web standards.

It wants IE unbundled or Windows to preinstall competitive browsers on the desktop.

And - and this seems extraordinary even for Europeans - it wants the EC to compel Microsoft to support open web standards "accepted by the web-authoring communities."

It's unclear what standards or web-authoring communities Opera has in mind exactly but some Internet sites still only open for IE.

The Oslo company's market share has been shrinking since Firefox picked up Netscape's fallen flag. It has retreated back to the mobile space with a 2% market share.

Opera says its complaint - the first since Microsoft lost its appeal of the EC's antitrust findings in the Court of First Instance in September - "calls on Microsoft to adhere to its own public pronouncements to support these standards, instead of stifling them with its notorious 'Embrace, Extend and Extinguish' strategy. Microsoft's unilateral control over standards in some markets creates a de facto standard that is more costly to support, harder to maintain, and technologically inferior and that can even expose users to security risks."

Opera's deputy general counsel Jason Hoida explained the company's legal position.

"The European Court of First Instance confirmed in September," he said, "that Microsoft has illegally tied Windows Media Player to Windows. We are simply asking the Commission to apply these same clear principles to the Internet Explorer tie, a tie that has even more profound effects on consumers and innovation. We are confident that the Commission understands the significance of the Internet Explorer tie and will take the necessary actions to restore competition and consumer choice in the browser market."

Of course, the EC's order to unbundle the Media Player from the operating system fell flat on its face. Consumers rejected the unbundled system.

And if the EC is tempted to act on Opera's complaint, it could be construed as rehearing the US antitrust case that Microsoft settled in 2004.

The European Committee for Interoperable Systems created by IBM, Oracle, and Red Hat, which held Microsoft's feet to the fire over the EC's antitrust order and which is hoping to get the commission seriously interested in defanging Vista somehow, has thrown its support behind its member's effort.

Its legal counsel Thomas Vinje put out a statement saying, "By tying its Internet Explorer product to its monopoly Windows operating system and refusing to faithfully implement industry-accepted open standards, Microsoft deprives consumers of a real choice in Internet browsers. Browsers are the gateway to the Internet. Microsoft seeks to control this gateway."

Vinje says Microsoft's failure to implement standards and its penchant for adding undisclosed proprietary extensions to those it does implement constitutes "unlawful exclusionary behavior" by a monopoly and violates Article 82 of the EC Treaty.

Microsoft claims consumers can use whatever browser they like.