https://techcrunch.com/2020/02/11/microsoft-launches-new-dev-tools-for-building-windows-10x-dual-screen-experiences/

At its Microsoft 265 Developer Day, Microsoft today debuted a number of new tools for developers who want to adapt their application to Windows 10X, the company’s version of Windows for dual-screen devices.

The highlight here is the launch of a Windows 10X emulator, which allows developers to preview what their applications will look like on a dual-screen device. As of now, there’s no Windows 10X hardware on the market after all. Microsoft’s own Surface Neo and a number of devices from various other manufacturers are slated to hit the market before the holidays, but by that time, Microsoft obviously wants developers to be ready for this new user experience.