Windows 10 build 17666 (rs prerelease)

Windows 10 build 17666 was released on 2018-05-09 for Insiders in the Fast and Skip Ahead rings.

Sets

 * Now features an acrylic title bar.
 * Microsoft Edge tabs will now be shown when you press Alt+Tab.
 * Functionality to mute tabs have been added.
 * Performance has been improved when restoring sets.
 * New option to give the user choice on if tabs should open in the same window or a new window.

Other

 * Cloud Clipboard support is now been enabled in the OS.
 * Dark theme support for File Explorer (still very early in this build).
 * Extended line endings support for Notepad.
 * Bing search support for Notepad.
 * Search for Windows 10 has been extended to support previews of apps, documents & more.
 * The ability to name groups on the tile folders.
 * Contains a questions section has been added to the Settings app which will show common questions asked by Windows users.

Build 17666 also includes some bug fixes which fix issues found in previous builds.