Currently, RadScheduleView supports keyboard navigation that works within the appointments area. To go outside of it, the control relies on the WPF default tab navigation logic (in this case allowed with Ctrl+Tab), but this doesn't work very well. Some elements (like the view definition buttons or input controls inside the appointment visuals) have their IsTabStop property set to False, which prevents the tab navigation.

Improve the accessibility of the control by allowing to navigate to the view definition buttons, the editors inside the appointment item and other interactive elements within the control (navigation buttons, calendar button, etc.). 

Consider implementing this via the existing NavigationBehavior if possible.