You can create a custom EditAppointmentDialog and use in the place of the default dialog. You can change the default dialog by handing AppointmentEditDialogShowing
event. Here is a code snippet which shows how to do it:
void radScheduler1_AppointmentEditDialogShowing(object sender, Telerik.WinControls.UI.AppointmentEditDialogShowingEventArgs e)
if (this.appointmentEditDialog == null)
this.appointmentEditDialog = new CustomAppointmentEditDialog();
e.AppointmentEditDialog = this.appointmentEditDialog;
inherits from EditAppointmentDialog
and all the child controls are protected modifiers. This means that you have access to the comboboxes and you can apply sorting.
Please write me back if you need more information.
All the best,
the Telerik team