Most notably, a mysterious "Microsoft Family" app bearing the Windows Live logo has appeared in the build. It's broken at this point, however, and only displays a white box when opened.
A subtle new option has also been added to the options menu of Microsoft's new Project Spartan browser: "Open in Internet Explorer." So while Microsoft's drawing a clear line between the two browsers by limiting its new rendering engine to Spartan alone, maybe Internet Explorer isn't being left for dead quite yet after all.
Given the polish already exhibited in the leaked universal Mail and Calendar apps, don't be surprised if you see them appear in an official Windows 10 preview build before long. Here are step-by-step instructions on how to start using Windows 10 today. Once you're rocking and rolling, be sure to check out these killer new features first — and these more advanced tips and tricks once you're ready to delve deeper.
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