private void btn_LinkChild_Click(object sender, RoutedEventArgs e)
 {
     if (lst_ChildBox.SelectedItem != null)
     {
         string           cID             = ((Child)(lst_ChildBox.SelectedItem)).ID;
         int              link            = 0;
         Link_DeLinkChild linkDelinkChild = new Link_DeLinkChild(link, cID);
         linkDelinkChild.ShowDialog(); //0 = link
     }
 }
 private void btn_De_LinkChild_Click(object sender, RoutedEventArgs e)
 {
     if (lst_ChildBox.SelectedItem != null)
     {
         string           cID             = ((Child)(lst_ChildBox.SelectedItem)).ID;
         int              delink          = 1;
         Link_DeLinkChild linkDelinkChild = new Link_DeLinkChild(delink, cID);
         linkDelinkChild.ShowDialog(); //1 = delink
         lst_ChildBox.Items.Clear();
         setChildBox();
     }
 }