Mozilla says that Microsoft will only allow IE to run in Windows RT, the version of Windows that will run on ARM computers. The scenario is reminiscent to a time when Microsoft tightly integrated IE into Windows 95/98, which eventually led to an antitrust lawsuit against the company that almost resulted in the breakup of the company.
Only the "Classic" environment of Windows RT is apparently affected, but Mozilla cries foul and says that Windows on ARM, "as currently designed", does not allow user choice, "reduces competition and chills innovation." Mozilla's General Counsel Harvey Anderson noted in a blog post:
"Windows on ARM prohibits any browser except for Internet Explorer from running in the privileged Windows Classic environment. In practice, this means that only Internet Explorer will be able to perform many of the advanced computing functions vital to modern browsers in terms of speed, stability, and security to which users have grown accustomed. Given that IE can run in Windows on ARM, there is no technical reason to conclude other browsers can’t do the same."
Windows RT Classic is believed to be a heavily restricted mode, in which only Microsoft code can be executed. Given the target market of Windows RT and especially entry-level notebooks that may not include touch screen support that can run the Metro interface, software vendors such as Mozilla may, in fact, be locked out of a substantial market. Firefox product manager Asa Dotzler explained that a Metro browser "does not have the APIs necessary to compete with IE or any other modern browser. On x86, Microsoft has given browser vendors the same privileges and APIs that IE uses. They have not done this on ARM."
Mozilla's only opportunity to offer Firefox is as a Metro app in a sandbox and cannot access Win32 APIs. Only Microsoft will be able to access both Metro and Classic features on ARM, Mozilla said. As the entry-level notebook market is shifting, this could turn into a tremendous problem for Mozilla, especially if Google is gaining traction with Chrome OS and locks out Mozilla from running Firefox on top of Chrome as well.
Anderson said that Mozilla encourages "Microsoft to remain firm on its user choice principles. Excluding 3rd party browsers contradicts Microsoft’s own published principles that users and developers have relied upon for years. These principles represented a Microsoft market approach that was both notable and went above and beyond their DOJ antitrust settlement obligations."