Two obstacles blocked the plaintiffs in consolidated cases against Microsoft Corp. from immediately appealing an order that rejected their request for certification as a class action. The first, based on Coopers & Lybrand v. Livesay, 437 U. S. 463 (1978), was that the order denying class status wasn’t a “final decision” under 28 U. S. C. §1291. And second, the 9th U.S. Circuit Court of Appeals denied a motion for interlocutory review under Federal Rule of Civil Procedure 23(f).Trying a third …