Hi @milesb, in addition to the basic samples included with the Core SDK available @ https://github.com/Tobii/CoreSDK
We have also created a series of samples to show developers how to use our Interaction API to build interactive eye tracking enabled games and applications. You can find these @ https://github.com/Tobii/interaction-samples
Here is included several methods of using fixations and gaze to select components on WPF forms amongst other things, so hopefully this should be exactly what you are looking for!
Please let us know if we can be of any further assistance.