//http://documentation.devexpress.com/#WindowsForms/CustomDocument2288 private void schedulerControl1_EditAppointmentFormShowing(object sender, AppointmentFormEventArgs e) { DevExpress.XtraScheduler.Appointment apt = e.Appointment; bool openRecurrenceForm = apt.IsRecurring && schedulerStorage1.Appointments.IsNewAppointment(apt); // Create a custom form. MyAppointmentForm myForm = new MyAppointmentForm((SchedulerControl)sender, apt, openRecurrenceForm); myForm.LookAndFeel.ParentLookAndFeel = schedulerControl1.LookAndFeel; e.DialogResult = myForm.ShowDialog(); schedulerControl1.Refresh(); e.Handled = true; }