I agree. Microsoft's strongest argument was that the features of an "OS" are fluid, ever-evolving, and un-definable. OS'es were all text-based, until one day th

I agree. Microsoft's strongest argument was that the features of an "OS" are fluid, ever-evolving, and un-definable. OS'es were all text-based, until one day they weren't and the GUI dominated. Win 95 had no Winsock or TCP/IP stack built-in, 98 did. File Explorer. Start Button. And as you say, the presence of MS Paint and the Calculator and Solitaire show that exact inclusions/exclusions are arbitrary. MS could have argued that it was it's responsibility -- obligation even -- to add new features and abilities to its OSes. Force the govt to "prove" that a browser is definitely an application and somehow cannot be a core part of the OS (otherwise there's no "bundling"). They wouldn't have been able to do that.