The complaint filed with Brazil’s antitrust authority, the CADE, accuses the software King of the World of bundling Edge into Windows in a way that makes it a monumental pain for users to switch. Opera reckons this gives the Redmond giant an illegal leg-up in the browser wars.

Opera general counsel Aaron McParlan said: “Microsoft thwarts browser competition on Windows at every turn. First, browsers like Opera are locked out of important pre-installation opportunities. And then Microsoft frustrates users' ability to download and use alternative browsers.”

The company is griping that Windows 11 doesn’t offer Opera as an option during setup and then makes it a chore for users to pick something else. Even if someone wants to install another browser, Edge allegedly throws tantrums with popups and prompts trying to guilt-trip users into staying.

It’s the same kind of fight that the big cheeses at the Mozzarella Foundation Mozilla had earlier this year, claiming that Vole was messing with users’ attempts to escape. Microsoft’s design antics seem carefully engineered to make swapping browsers feel like trying to exit a dodgy gym membership.

Opera says it is the third most popular browser in Brazil, lagging behind Chrome and Edge. But with Edge’s position propped up by what Opera calls “manipulative” design choices and bundling, it wants regulators to step in and force a bit of fair play.