Given that Spartan has not been included in any publicly available Windows 10 preview release, how, exactly, would you expect there to be support for it from an open source project like Selenium? Do we plan to support it? Yes, I certainly hope to. In an ideal world, the W3C spec for WebDriver will have matured to the point that Microsoft can provide day-and-date support at release time. But how about we let the browser at least be available in a preview for a reasonable time before asking about support, okay?