Opera has filed an antitrust complaint with Brazil's Administrative Council for Economic Defense (CADE) accusing Microsoft of employing manipulative design tactics to unfairly promote its Edge browser over competing browsers on Windows. The Norwegian browser maker alleges that Microsoft uses dark patterns and other anticompetitive practices that discourage users from trying third-party browsers, effectively locking them into Edge. Opera's complaint highlights concerns about Microsoft's default settings and user interface strategies that favor Edge, raising issues of browser choice fairness. The complaint in Brazil is part of a broader dispute, with Opera asserting that these tactics affect users globally. This development follows ongoing tensions between Microsoft and rival browser makers over market competition. Separately, LibreOffice has accused Microsoft of undermining open-source software by blocking the account of one of its engineers.