> If the RecurrenceRule is null (e.g. the appointments is not a recurring one) - the checkbox will be unchecked. Otherwise the checkbox must be checked."
In Telerik.Web.UI (version 2011.1.413.35), this is not correct. Even if the checkbox is ticked, the RecurrenceRule is still null. The only time, the RecurrenceRule is populated is when a Frequency radio button has been selected. So the way to access the checkbox, as our team lead suggested, was to manually find the checkbox control within the RecurrenceEditor container and then access it's value. Example shown below in C#:
//NOTE: "RecurrentAppointment" is the internal name of the checkbox in the RecurrenceEditor
CheckBox cbRecurrentAppointment = (CheckBox)ffRecurrenceEditor.FindControl("RecurrentAppointment");
if (cbRecurrentAppointment != null)