A Microsoft shareholder has sued the company over failing to implement a browser choice screen into Windows, as previously required by European Union regulators.

Shareholder Kim Barovic claims that both former CEOs, Bill Gates and Steve Ballmer, failed to properly manage the company, marking the first major revolt within the ranks since last year's EU ruling.

An investigation by European antitrust bodies found that between May 2011 and July 2012, as many as 15 million users were not given a browser choice, despite a previous agreement by Microsoft in 2009 to address the issue.

The result was a fine of €561 million (£464 million, $732 million, AU$825 million), the first of its kind in Europe.

Executive responsibility

As perhaps a stronger motivation for those at the top, then CEO Steve Ballmer and then head of Windows Steven Sinofsky both had cuts to their bonuses. Ballmer has since been replaced by Satya Nadella, and Sinofsky left Microsoft altogether, with Julie Larson-Green taking his place.

Barovic wants the Board of Directors to launch a thorough investigation of its own, but Microsoft has resisted this demand. She claims that the firm refused to take action against executives who had not fulfilled their duties.

"Ms. Barovic asked the board to investigate her demand and bring a lawsuit against the board and company executives. The board thoroughly considered her demand as she requested and found no basis for such a suit," Microsoft said in a statement, according to PC Pro.