Microsoft today released a new Windows 10 preview for PCs with Sets, Bluetooth, and Calculator improvements. 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 (this month), 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.

Sets, which isn’t necessarily its final name, is a feature that lets you run multiple apps in a single window, using tabs. 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.

Sets now lets you drag and drop app tabs across windows and use Alt + Tab to move between tabs. Sets now also has its own settings section (Settings => System => Multitasking) and is searchable (type “sets” or “tabs”). There is a new keyboard shortcut (Ctrl + T) for opening a new tab in a File Explorer window, a new user interface for opening new tabs and windows in the File Menu, and an option to open a folder in a new tab via the context menu. If you right-click on a Sets tab, you’ll see new options, including “close other tabs,” “move to new window,” and “close tabs to the right.” Other Sets improvements center around restoring Previous Tabs, along with the usual bug fixes.

You can now check the battery of your Bluetooth devices in “Bluetooth & other devices.” The battery percentage will update whenever your PC and the device are connected.

Windows Calculator has been updated (version 10.1803.711.0) to fix a small but serious bug. The app now correctly calculates square roots for perfect squares (integers that are squares of other integers). Previously, the calculation was only an approximation.

This desktop build includes the following general bug fixes and improvements:

  • Fixed an issue resulting in duplicate entries in Disk Management.
  • Fixed an issue that could result in certain UWP apps silently terminating when minimized.
  • Fixed an issue resulting in certain devices with BitLocker enabled unexpectedly booting into BitLocker recovery in recent flights.
  • Fixed a race condition that could result in the taskbar not autohiding after opening and closing the Start menu while a fullscreen window was visible.
  • Fixed an issue where typing in Start would switch to a blank Cortana screen if Start was open when the PC went to sleep.
  • Fixed an issue when using Arabic as your display language where after using the X to close the touch keyboard in a UWP app text field it might stop coming up automatically in that field.
  • Consolidated the places where users can adjust their display brightness by removing the display brightness slider in Control Panel Power Options and the “Display brightness” section under Power Options Advanced Settings. You can still adjust your display brightness via Settings > System > Display settings, the Action Center, and via keyboard hot keys.

Today’s update bumps the Windows 10 build number for the RS5 branch from 17634 (made available to testers on March 29) to build 17639.

This build has three known issues:

  • If you open Settings and clicking on any links to the Microsoft Store or links in tips, Settings will crash. This includes the links to get themes and fonts from the Microsoft Store, as well as the link to Windows Defender.
  • On resuming from sleep, the desktop may be momentarily visible before the Lock screen displays as expected.
  • When Movies & TV user denies access to its videos library (through the “Let Movies & TV access your videos library?” popup window or through Windows privacy settings), Movies & TV crashes when the user navigates to the Personal tab.

As always, don’t install this on your production machine.