public void Add(CombineEntry entry)
 {
     list.Add (entry);
     if (parentCombine != null) {
         entry.SetParentCombine (parentCombine);
         parentCombine.NotifyEntryAdded (entry);
     }
 }
 public void Remove(CombineEntry entry)
 {
     list.Remove (entry);
     if (parentCombine != null) {
         entry.SetParentCombine (null);
         parentCombine.NotifyEntryRemoved (entry);
     }
 }