private void OnRelationCollectionChanged (object sender, CollectionChangeEventArgs args)
{
/* PropertyDescriptor Add */
if (args.Action == CollectionChangeAction.Add)
OnListChanged (new ListChangedEventArgs (ListChangedType.PropertyDescriptorAdded,0,0));
/* PropertyDescriptor Removed */
if (args.Action == CollectionChangeAction.Remove)
OnListChanged (new ListChangedEventArgs (ListChangedType.PropertyDescriptorDeleted,0,0));
/* FIXME: PropertyDescriptor Changed ???*/
if (args.Action == CollectionChangeAction.Refresh)
OnListChanged (new ListChangedEventArgs (ListChangedType.PropertyDescriptorChanged,0,0));
}