Gets or sets the condition for display of the Navigation Buttons.
Navigation buttons are visible if there are no appointments displayed within the current view area.
Navigation buttons are always visible.
Navigation buttons are always hidden.
Use the NavigationButtonVisibility property to specify that the Navigation Buttons are always visible, always hidden, or whether its visibility is decided by the SchedulerControl. The latter means that they are visible when the current view doesn't have any appointments within its visible working area.