Microsoft have finally added support for using the Surface Dial on the screen of the Surface Pro 4. You can now place the dial on the screen of the Surface Pro 4 and then apps like Photoshoot can interact with it. So far not many developers have added support for the Dial. I can only think of Adobe Photoshop, Drawbord PDF and Sketch that make good use of it.
Support was been added as part of an April firmware update that is rolling out now:
The following updates are delivered to Surface Pro 4 devices on Windows 10:
Surface – Human Interface Device – 2.0.313.0
Surface Digitizer Integration – Human Interface Device2.0.313.0 enables on-screen support for Surface Dial.
Surface – Firmware – 188.8.131.52
Surface Touch – Firmware
184.108.40.206 enables on-screen support for Surface Dial and improves touch accuracy.
Surface – System – 220.127.116.11
Surface Dial Detection – System
18.104.22.168 enables on-screen support for Surface Dial.
Surface – System – 1.0.821.0
Surface Touch Servicing ML – System
1.0.821.0 enables on-screen support for Surface Dial and improves touch accuracy.