Atop the new investigation into Microsoft's failure to give some Windows users a browser ballot screen, European Union (EU) antitrust officials are also looking into charges that Microsoft has blocked rival browser makers from harnessing the power of Windows 8 for their software, according to the Reuters news service.
Earlier Wednesday, Reuters reported that the European Commission had launched an inquest into accusations that Microsoft stymies other browser makers' efforts to build software that runs in Windows 8 and the offshoot designed for ARM-powered tablets, Windows RT.
The new investigation is part of the one the Commission opened Tuesday, when it said Microsoft broke a three-year-old agreement by failing to supply a "browser choice" screen to customers running Windows 7 Service Pack 1 (SP1).
According to Reuters, a Commission spokesman confirmed that antitrust officials are also looking into allegations that Microsoft refuses to give rivals full access to APIs (application programming interface) in both Windows 8 and Windows RT.
The Windows RT APIs have been the source of tension between Microsoft on one hand, and Mozilla and Google on the other.
Two months ago, Mozilla's lead lawyer and one of its Firefox directors accused Microsoft of withholding APIs necessary to build a competitive browser for Windows RT, and said the behavior "may have antitrust implications."
Those Mozilla officials noted that Microsoft has given full API access only to the latter's own Internet Explorer 10 (IE10), the sole browser that will run on Windows RT's conventional desktop. Also, sans those APIs, it will be impossible to create a viable Metro-style browser for Windows RT, Mozilla has contended.
"We could build a beautiful Firefox that looked really nice on Metro, but Firefox would be so crippled in terms of power and speed that it's probably not worth it to even bother," said Asa Dotzler, director of Firefox, at the time.
Google said it "share[ed] the concerns Mozilla has raised" when the issue came up two months ago.