protected override void ChangeArrowOrientationProperty(iEditSL.Entities.ArrowOrientations orientation)
 {
     switch (orientation)
     {
         case ArrowOrientations.None:
             ArrowFrom.Visibility = Visibility.Collapsed;
             ArrowTo.Visibility = Visibility.Collapsed;
             break;
         case ArrowOrientations.OneWay:
             ArrowFrom.Visibility = Visibility.Collapsed;
             ArrowTo.Visibility = Visibility.Visible;
             break;
         case ArrowOrientations.TwoWay:
             ArrowFrom.Visibility = Visibility.Visible;
             ArrowTo.Visibility = Visibility.Visible;
             break;
     }
 }
 protected override void ChangeArrowOrientationProperty(iEditSL.Entities.ArrowOrientations orientation)
 {
 }