Windows Wheel devices, such as the Surface Dial, are a new category of input device that enable compelling and unique user interaction experiences for Windows and Windows apps.
With a form factor based on a rotate action (or gesture), the Surface Dial is intended as a secondary, multi-modal input device that complements input from a primary device. In most cases, the device is manipulated by a user’s non-dominant hand while performing a task with their dominant hand (such as inking with a pen). It is not designed for precision pointer input (like touch, pen, or mouse).
Microsoft yesterday published a new video for developers about how to build UWP apps that support Windows wheel devices, such as the Surface Dial. They have explained the RadialController APIs to customize both the tools on the integrated menu and how the app can respond to wheel input. Even though they use the Surface Studio to demonstrate the full power of the Surface Dial and RadialController APIs, any PC, laptop, or tablet with the Windows Anniversary Update supports the Surface Dial in off-screen mode.