private bool CanShowInVarietyPairs()
{
if (_selectedWords.Count != 2)
return false;
Word w1 = _selectedWords[0].DomainWord;
Word w2 = _selectedWords[1].DomainWord;
if (w1.Variety == w2.Variety)
return false;
VarietyPair vp = w1.Variety.VarietyPairs[w2.Variety];
WordPair wp;
if (vp.WordPairs.TryGetValue(_selectedMeaning.DomainMeaning, out wp))
return wp.GetWord(w1.Variety) == w1 && wp.GetWord(w2.Variety) == w2;
return false;
}