In the latest Redstone 5 skip ahead build for Windows 10 Insiders, Microsoft has added a hidden feature that enables a dark theme in File Explorer. While the new theme is in the very beginning development stages (hopefully!!), it's currently not a sight to behold.
First discovered by Windows expert Rafael Rivera in the release of build 17650, this feature can be enabled using the mach2 application. Mach2 is a program created by Rivera that can be used to search for hidden features and enable them. This allows you to play with features that are currently in development or used for testing purposes.
Oh no, FileExplorerDarkTheme is coming.— Rafael Rivera (@WithinRafael) April 20, 2018
With only the tab bar and navigation bar currently using the dark background, this theme currently looks awkward at best. Thankfully, this is a feature that is in very early development and requires a special tool to even enable it, so we shouldn't read too much into it yet.
For those who want to play with it in build 17650, you can compile the mach2 application and enable it using the "mach2 enable 10397285" command.