public KeysCollection(MtObservableSortedDictionary <TK, TV> owner) : base(owner, x => x.Key) { }
public ValueCollection(MtObservableSortedDictionary <TK, TV> owner) : base(owner, x => x.Value) { }
protected ProxyCollection(MtObservableSortedDictionary <TK, TV> owner, Func <KeyValuePair <TK, TV>, TT> selector) { Owner = owner; _selector = selector; }