Windows watcher Paul Thurrott is reporting that, according to his sources, Microsoft will start talking about a new Windows version, codenamed Threshold, at its BUILD conference in April. Thurrott says that this version will be released, probably with the name Windows 9, a year thereafter.

Details of Threshold are thus far scarce, but a few things are notable. Thurrott says that there won't be an alpha or beta in time for the BUILD conference, and the product won't even begin development until April. Rather, the company will outline its vision and talk about what Threshold will contain.

Microsoft is striving to reach a happy medium between the extreme sharing and openness of the Longhorn project—in which the company talked up a lot of things that were either never delivered at all, or never delivered in the way originally described—and the extreme secrecy of Windows 7 and 8 that was the hallmark of Steven Sinofsky's reign at the company.

One hopes that this will bring more receptiveness to feedback. Problems with Windows 8—its inconsistent approach, its lack of tutorial, the failure to clearly distinguish between Windows 8 and Windows RT—were all reported, both within Microsoft and from outside, during Windows 8's development. They were met with assertions that the perceived problems were not real problems and that no changes were necessary. When Windows 8 shipped, it became clear that they were, in fact, real problems. Windows 8.1 did a lot to address them, but perhaps not enough.

With this "vision" announcement, Microsoft will hope to drum up some excitement and interest in Windows. This is something the company has lacked for a long time, and it's not clear it will ever return. It's a double-edged sword. There was excitement and interest, back in the day, in the Longhorn vision—new programming model, fancy new filesystem, GPU-accelerated graphics, and more—but Microsoft's failure to temper that vision was, I think a partial cause for the Windows Vista backlash. Microsoft made grand promises, failed to clearly walk them back, and then delivered on virtually none of them.

In the light of this, we can expect the Threshold announcement to be a little more grounded. For Longhorn, Microsoft was promising things that were hard to solve even in theory. These problems turned out to be impractical to solve in practice, and so it was little surprise that Microsoft didn't deliver the promised software. The Threshold announcement should be much more realistic while still being enough to interest people.

Between BUILD and next April's release, Thurrott writes that Microsoft plans to have three milestone builds, though he doesn't know which, if any, will be made publicly available.

So what'll be in Threshold? The two things Thurrott says are a way of running Metro apps on the desktop and a reinstatement of the Start menu. Our sources say that's only sort of true, and that it won't be the Start menu as such but rather something new. Start menuesque, perhaps, but not a literal Start menu.

There are already third party apps for reinstating the Start menu and running Metro apps within Windows. Most of them leave something to be desired, for example by squandering good parts of the Start screen such as its live tiles and 2D organization. Sticking Metro apps into windows also isn't particularly streamlined. Metro apps, particularly in Windows 8, can make various assumptions about their size that windowed apps can't. Putting them in arbitrarily sized windows breaks those assumptions.

A proper, first-party solution is certainly feasible. Designer Jay Machalani created a set of neat mockups of how a more coherent Windows might look, and his concepts are striking because rather than being simply a reversion to Windows 7, they do appear to fuse the best of both worlds. This is not to say that Microsoft will do anything quite this adventurous.

Little else is even speculated about Threshold, except for one thing it won't be: according to Mary Jo Foley, it won't be the unified Windows operating system that Microsoft will eventually deliver in one form or another.