Hi @eyerpheus, an update ont this issue.
After conferring with colleagues, I can confirm that unfortunately it is not possible to alter the gaze aware region for the radio button WPF component.
Accordingly you can either separate the distance between existing radio buttons (which would seem the route involving the least coding) or alternatively choose instead a polygonal shape as the WPF component for which you can more easily adjust the gaze aware area. (the Gaze aware area is automatically configured as the polygon shape area by default).
An example of how you can accomplish this in included with the Core SDK samples, specifically the “Interaction_VirtualWindows_101” sample application.
Sorry to bring you disappointing news, but hopefully you can alter your program without too much issue. Please let us know if we can be of further assistance.