The first idea was to move KeyboardBehavior from SimpleCalc to Toolkit, so we can add keyboard support to SimpleCalc.

What is needed is a way to fire a command when a key is released on a physical keyboard to have a VirtualKey inputed.

Current usage on SimpleCalc:

<Page ... xmlns:keyboard="using:SimpleCalculator.Keyboard" keyboard:KeyboardBehavior.KeyUpCommand="{Binding InputVirtualKey}">

For reference of the command see: InputVirtualKey

The behavior would make sense also to support generic keyboard input without adding a button for each char in the UI.