The OnClientAppointmentContextMenuItemClicking client-side event is called when an appointment context menu item is clicked,before RadScheduler processes the click event.
Two parameters are passed to the event handler:
sender is the scheduler client object.
eventArgs has the following methods:
get_appointment() - the instance of the appointment.
get_item() - the clicked menu item.
set_cancel() - used to cancel the event.
This event can be cancelled.