Hello Leon, 

Thank you for contacting Infragistics. This is considered to be a new product idea. Existing appointments temporarily adjust during a drag operation and there is no way of turning it off. You can cancel the drag event and play around with snapping an appointment to what ever date you want starting with the AppointmentsDragging but since it fires as soon as you move your mouse to the destination date it's difficult to cancel this event only in this unique situation. 

private void UltraDayView1_AppointmentsDragging(object sender, AppointmentsDraggingEventArgs e)
{
//check if another appointment 
Appointment appt = e.Appointments[0];
e.Cancel = true;
appt.StartDateTime = DateTime.Now;

}

You can suggest new product ideas for future versions (or vote for existing ones) at <www.infragistics.com/.../ideas>.
Submitting your idea will allow you to communicate directly with our product management team, track the progress of your idea at any time, see how many votes it got, read comments from other developers in the community, and see if someone from the product team has additional questions for you.
Remember when submitting your idea to explain the context in which a feature would be used and why it is needed as well as anything that would prevent you from accomplishing this today. You can even add screenshots to build a stronger case. Remember that for your suggestion to be successful, you need other members of the community to vote for it.

Let me know if you have any questions.

Michael DiFilippo
Software Developer
Infragistics, Inc.