private void popup_Opened(object sender, EventArgs e)
{
PopupView.MoveFocus(new TraversalRequest(FocusNavigationDirection.First));
if (SelectedForeignKey == 0)
{
SetSelectedForeignKey();
}
var iNotify = PopupView.DataContext as INotifyPropertyChanged;
if (iNotify != null)
{
iNotify.PropertyChanged += INotify_PropertyChanged;
}
}