public override void Visit(PKGridColumnRow item)
 {
     if (currentItem is PKColumn)
     {
         item.Add(currentItem as PKColumn);
     }
 }
 public override void Visit(PKGridColumnRow item)
 {
     canAddVisitor = new PKItemCanAddVisitor(newItem);
     item.Accept(canAddVisitor);
     if (canAddVisitor.CanAdd)
     {
         item.Add(newItem as PKColumn);
         this.Added = true;
     }
 }