Hi,

The XAML team has recently reviewed this feature request and decided to decline it. The main reason why we decided to do so is that the default Silverlight and WPF controls are exposing their selection as a read-only property and we wanted to be consistent with these controls (like ListBox, DataGrid, TabControl, etc.). However, we have created an SDK Example that demonstrates how to easily set the SelectedAppointments property to a collection of Appointments using an attached property. The sample could be found on the following link:
https://github.com/telerik/xaml-sdk/tree/master/ScheduleView/SettingSelectedAppointments

Regards,
Nasko