Это то, что я использую в WPF - я полагаю, вы используете Silverlight, поэтому YMMV:
//in your window's constructor, add:
Sched.AddHandler(AppointmentItemsControl.SelectionChangedEvent, new SelectionChangedEventHandler(ShowCustomApptForm), true);
//then handle the event like this:
public void ShowCustomApptForm(object sender, SelectionChangedEventArgs args)
{
if (args.AddedItems.Count > 0)
{
AppointmentSlot item = args.AddedItems[args.AddedItems.Count - 1] as AppointmentSlot;
if (item != null)
{
//Get the appointment object so we can access the UniqueID
Appointment SelAppt = (Appointment)item.Occurrence.Master;
//Open the custom form, passing the uniqueid to the constructor
MyCustomForm ApptFrm = new MyCustomForm(Convert.ToInt32(SelAppt.UniqueId));
ApptFrm.Show();
}
}
}