Microsoft today released a new Windows 10 preview for PCs with acrylic in the sign-in screen. This build is from the 19H1 branch, which, as its name indicates, will arrive in the first half of next year. Microsoft is simultaneously in the process of finalizing the RS5 branch, which represents the Windows 10 update the company plans to release in October.

Windows 10 is being developed as a service, meaning it receives new features on a regular basis. Microsoft has released five major updates so far: November Update, Anniversary Update, Creators Update, Fall Creators Update, and April 2018 Update.

Microsoft’s Fluent Design has spread to the Window sign-in screen. The acrylic is now visible on the sign-in screen background, an effect Microsoft has given an over-the-top description: “The translucent texture of this transient surface helps you focus on the sign-in task by moving the actionable controls up in the visual hierarchy while maintaining their accessibility.”

Right.

Separately, Microsoft has renamed “Microsoft Apps” as “Your Phone Companion.” This is meant to bring the Android app inline with the Your Phone app, which lets you access your phone’s content — like text messages, photos, and notifications — right on your Windows 10 PC.

Bug fixes and known issues
This desktop build includes the following general bug fixes and improvements (many will sound familiar to those following updates on the RS5 branch):

Fixed an issue where Task Manager couldn’t be resized in the previous flight.
Fixed and issue resulting in Settings crashing when navigating to Accounts > Sign-in in the previous flight.
Fixed an issue resulting in reduced Action Center reliability in recent flights.
Fixed an issue where if you opened one of the taskbar flyouts (like network or volume), and then quickly tried to open another, it wouldn’t work.
Fixed an issue for people with multiple monitors where if the Open or Save Dialog was moved between monitors some elements might become unexpectedly tiny.
Fixed an issue resulting in certain apps crashing recently when setting focus to the in-app search box.
Fixed an issue resulting in certain games, like League of Legends, not launching/connecting properly in recent flights.
Fixed an issue where clicking on web links in PWAs such as Twitter didn’t open the browser.
Fixed an issue resulting in certain PWAs not rendering correctly after the app had been suspended then resumed.
Fixed an issue where pasting multi-line text into certain websites using Microsoft Edge might add unexpected empty lines between each line.
Fixed a crash in recent flights when using the pen to ink in Microsoft Edge’s web notes.
Fixed a high hitting Task Manager crash in recent flights.
Fixed an issue resulting in Settings crashing for Insiders with multiple monitors when changing various options under Display Settings in the last few flights.
Fixed a crash when clicking the Verify link on the Accounts Settings page in recent flights.
Added a new group policy for preventing the use of security questions for local accounts. This can be found under Computer Configuration > Administrative Templates > Windows Components > Credential User Interface.
Fixed an issue where the contents of the Apps & Features page wouldn’t load until the apps list was ready, resulting in the page appearing blank for a time.
Fixed an issue where the list on Settings of built-in phrases for the Pinyin IME was blank.
Fixed an issue in Narrator where activating Microsoft Edge history items would not work in Scan mode.
Improvements in Narrator Selection when moving forward in Microsoft Edge.
Fixed an issue where Narrator would incorrectly report some standard combo boxes as “editable combo box” instead of “combo box”.
Today’s update bumps the Windows 10 build number for the 19H1 branch from 18234 (made available to testers on September 6) to build 18237.

This build has three known issues:

Narrator sometimes does not read in the Settings app when you navigate using Tab and arrow keys. Try switching to Narrator Scan mode temporarily. And when you turn Scan mode off again, Narrator will now read when you navigate using Tab and arrows key. Alternatively, you can restart Narrator to work around this issue.
You may notice the background of notifications and the Action Center lose color and become transparent (with an acrylic effect).
If you install any of the recent builds from the Fast ring and switch to the Slow ring – optional content such as enabling developer mode will fail. You will have to remain in the Fast ring to add/install/enable optional content. This is because optional content will only install on builds approved for specific rings.