In 2007, the "fluent UI" or ribbon had IP rights asserted and required a license from Microsoft. That license is now no longer available, the page only stating 'retired'.
What is the status of using a ribbon UI on Windows or any other platform? Is Microsoft still asserting IP rights, and is a license required?
Note that there are many questions online about this, but no answer, much less a sourced one stating Microsoft's official position. This leaves many developers in a state of uncertainty.
As of 2017:
- No documentation on MSDN anywhere mentions a license. Consider, for example, the MFC ribbon overview.
- The VC++ 2017 MFC
CMFCRibbonBar
class, the only ribbon installed with VS2017, links to the retired license in its header. This header has not changed for many years. Its documentation does not mention a license. - The Visual Studio 2017 license does not mention the ribbon.
- The Windows 10 SDK license does not mention the ribbon (checked against 10.0.15603.137, downloaded 2017-04-11.)
- Some believe this means no-one who did not sign a license before it was retired are able to legally use a ribbon.
- A 2009 comment in a forum (not a good basis) states there are "no unusual licensing requirements".
- There has been no statement by Microsoft of a change in its attitude the the ribbon, arguably meaning that now a license is no longer available, no developers can use a ribbon.
- Microsoft uses a ribbon in its macOS Office applications, but has not indicated if other developers may use a ribbon on non-Windows platforms
- There is significant doubt if the ribbon is valid IP.
This leaves all developers who did not sign a license prior to it being retired in limbo and uncertainty, not knowing:
- If they can use the inbuilt WinAPI ribbon control on Windows 10 without a license
- If they can use a third party ribbon control on Windows without a license
- If they can use a third party ribbon control on macOS or Linux
- If they can use a ribbon for an application that competes with a Microsoft application (either Office, or other.)
Please cite sources, and prefer the kind of sources you could quote if it became legally important, above sources that are a comment on a forum. I'm seeking a definitive answer, and won't mark a "it's probably ok, you'll get away with it" answer as correct.