After releasing a new Windows 10 build from the RS4 branch yesterday, Microsoft today released a new Windows 10 preview for PCs that brings back the new Sets feature. This build is from the RS5 branch, which represents the Windows 10 update the company plans to release much later this year. The next update will come sooner, sometime this spring, from the RS4 branch.

Windows 10 is a service, meaning it was built in a very different way from its predecessors so it can be regularly updated with not just fixes, but new features, too. Microsoft has released four major updates so far: November Update, Anniversary Update, Creators Update, and Fall Creators Update.

This RS5 build is for Windows Insiders who have chosen the Skip Ahead option, meaning they continue to receive builds from the RS_PRERELEASE branch. Only a small subset of Insiders can opt into Skip Ahead, as Microsoft still needs testers helping with RS4.

The only major change in this release is the return of a feature that first debuted last year but didn’t make the cut for the RS4 update. Sets, which isn’t necessarily its final name, introduces tabs in various apps. The idea is that you should be able to open new tabs in a given window for whatever you’re working on: relevant webpages, research documents, necessary files, and so on. This completely flips the idea of “windows” in Windows on its head, as one app’s window can be used to open tabs that have other apps.

Sets currently works with first-party apps Mail, Calendar, OneNote, MSN News, Microsoft Edge, and Windows itself for a more “seamless experience.” The feature is…