Ribbon is really great, but you cannot just use it for free for Office-competing products: "There’s only one limitation: if you are building a program which directly competes with Word, Excel, PowerPoint, Outlook, or Access (the Microsoft applications with the new UI), you can’t obtain the royalty-free license"

https://blogs.msdn.microsoft.com/jensenh/2006/11/21/licensin...

Except if you probably pay MS a royality fee.