Of those 1.5 million, 450,000, about 30 percent, are "highly active" testers putting the preview build of Windows 10 client through its paces daily, officials said in a new blog post.
Officials said Windows 10 testers are using Windows 10 test builds more actively than participants in preview and beta programs for Windows 7, 8 or 8.1. Microsoft has fixed almost 1,300 Windows 10 preview bugs reported and/or up-voted by testers, officials added.
"We've been very hard at work putting together a great build for you that includes a bunch of new features and improvements. As all of those payloads came in we needed to stabilize code, fix any integration issues, and ensure all of the new UX is polished. We're really focused on making the next build something that we hope you'll think is awesome. In fact, just so that we have a *daily* reminder to ourselves that we want this build to be great, we even named our build branch FBL_AWESOME. Yeah, it's a bit corny, but trust me that every Dev that checks in their code and sees that branch name gets an immediate reminder of our goal."
Microsoft also is expected to show off at that event its Windows 10 mobile preview, which is expected to run on Intel- and ARM-based tablets, as well as Windows Phones. Microsoft's OSG is hustling to make the mobile preview available to testers by January 21 or shortly thereafter, sources say.