How to implement drag-and-drop appointment functionality between two SchedulerControls

By default, the drag-and-drop appointment functionality between two SchedulerControls is supported.

However, SchedulerControl always removes an appointment after moving it to another SchedulerControl. 
Nevertheless, it is possible to implement this behavior manually by handling the AppointmentDrag, AppointmentsChanged andAppointmentDeleting events, and preventing appointment deletion in the AppointmentDeleting event handler.

Take special note that both SchedulerControls should have the same mappings to custom fields to prevent losing data from these fields after moving an appointment.
Thus, it's necessary to set custom field mappings for the storages manually using the SchedulerStorage.Appointments.CustomFieldMappings.Add method.