Windows Sets might sound familiar to plenty of tech fans around the world, and especially to Windows 10 users. But not everyone might be able to tell you what Sets is. And that’s because Microsoft never made the feature available to Windows 10 users.

Announced last year, Sets is quite possibly one of the coolest Windows features ever invented. What it does is something that seems extremely simple, on the surface. But it’s also a complicated thing to pull off, for the operating system, and, hence, Microsoft.

Microsoft Sets gives you a tabbed window experience similar to what you’d find in an internet browser. The brilliance of it is that not every tab must belong to the same application. So, you could have a bunch of apps opened in the same window, including browsers, Office documents, and pretty much anything else that can run on Windows 10. Have a look at this video to understand precisely how Sets is supposed to work and simplify your workflow in the process:

Yes, that’s an early look at Sets, and Microsoft is not ready to let you use it. Per The Verge, the feature isn’t even available in the latest Windows 10 test build. So if you’ve been trying Sets for the past few months, get ready to say your goodbyes now. Microsoft pulled Sets from the latest beta build, and the feature isn’t to return in time for Microsoft’s next major Windows 10 update, which is due this fall.

Sources familiar with Microsoft’s plans told the tech blog that Microsoft is looking to tweak and improve the tabs integration in apps including Edge and Microsoft Office.

Microsoft mentions precisely the same thing in the changelog posted for beta build 17704:

Thank you for your continued support of testing Sets. We continue to receive valuable feedback from you as we develop this feature helping to ensure we deliver the best possible experience once it’s ready for release. Starting with this build, we’re taking Sets offline to continue making it great. Based on your feedback, some of the things we’re focusing on include improvements to the visual design and continuing to better integrate Office and Microsoft Edge into Sets to enhance workflow. If you have been testing Sets, you will no longer see it as of today’s build, however, Sets will return in a future WIP flight. Thanks again for your feedback.

While it may be disappointing to see Sets go, for the time being, let’s remember that Microsoft never committed to a launch time frame for the feature. And if Microsoft thinks the feature has to be retired, for the time being, it’s probably for the best.