Delivering on its promise to push out builds to the Fast ring on a speedier basis to testers and developers playing with Windows 10 Technical Preview, Microsoft released build 10049 Monday and it's the first one involving the impending new browser codenamed Project Spartan.

Noting that last week's builds were "BIG" ones as well, the most current release illustrates the steady progress being made with Build 10049 is about a week newer than the release of build 10041 for PCs.

What that means, according to Microsoft's Windows blog, is that while this release boasts Project Spartan involvement it's basically a mix of fixes and tiny improvements.

The blog then lists out issues corrected, such as PC freezes when manually locking a PC and windows showing up on the desktop behind several tasks such as Start Screen and Snap Assist.

The blog also notes several known issues for the current build, including a blue screen popping up after logging in and Outlook email indexing not working.

"As I mentioned on Friday, we are also working on the next build of Windows 10 for phones and plan to support a bunch of additional phones in the next build for phone as well as some great new features. As always, I'll share info with you on that as soon as I can," writes Gabe Aul.

Noting that the build is focused heavily on Project Spartan, Aul acknowledges there is still a "ton of work" to do with Spartan.

"As with all other new features we've introduced, we have a ton of work left to do with Spartan so expect to see some bugs and rough edges in this first preview. As always, we look forward to hearing your feedback via the Windows Feedback App," writes Aul.

According to one report, the initial Spartan preview does feature a good amount of the functionality previewed back in late January when Microsoft demoed Spartan at a Windows 10 event.

The initial Spartan peek includes the integration of the new browser and Microsoft personal digital assistant technology Cortana. It also includes the capability to annotate webpages with a mouse or a pen.

Aul, in a blog post this past weekend, wrote Microsoft is also prepping the next test release of its Windows 10 Mobile and that it's on schedule to support most Lumia Windows Phones.

"This testing will allow us to support A LOT more phones for the next flight. I get a ton of questions every day on Twitter about when your favorite phones will be usable, and I'm happy to report that the vast majority will be supported with the next flight (full list below)," wrote Aul.

Microsoft has said that Windows 10 will hit the market later in 2015.