Microsoft released another new Windows 10 19H1 test build to Fast Ring Insiders on February 1. That build -- No. 18329 -- adds some more incremental features to the next feature update for Windows 10.
Build 18329 includes a quick-access capability for most used apps in Search. It also adds the ability to launch Win32 desktop apps, such as Spotify, Paint.NET and Visual Studio Code, in Windows Mixed Reality in the same way users can launch Store apps. (Users already could launch Win32 apps in Mixed Reality, but not simply or directly.)
Microsoft made some additional tweaks to other related apps as part of today's rollout. A new update to Mail & Calendar adds Dark mode for Mail and Calendar items. It also adds a Default font feature allowing users to customize how new messages will look.
Microsoft earlier this week opened up access to the "Skip Ahead" Ring for testers who want early access to the next Windows 10 feature update. That update, known as "Vanadium" and/or 19H2, is slated to roll out to mainstream users around October 2019. Windows 10 19H1, also known as 1903/April 2019 update, should be finalized by March 2019 and start rolling out to mainstream users around April 2019.