Is there a Win32 API yet for Windows 10 v1809 Sets?

The next release of Windows 10 adds a new UI feature which, best as I can understand, is tabbed windowing with the twist that tabs can come from different applications. Or, put another way, it’s a modern take at Binder:

Microsoft Office Binder http://jdstiles.com/mso2k/binder/msbinder.gif

Recent builds have started some limited support for Win32 apps:

Sets is now enabled for most desktop (Win32) apps that use a default and non-customized title bar. Apps that customize their title bar will not have Sets (e.g. Paint.exe).

Suppose I do customize my title bar — is there an API yet that helps me integrate my app with this?