So often when I go up to get my daughter sorted in her room, my neighbour is visible from what I assume is her room.
She has 2 young children of her own for context
My daughter is 4 and said this morning 'look mummy, the neighbour lady has her boobies out' 
Would you tell your neighbour you can see them? Do you think she knows this and just isn't putting curtails up
I and my husband have also seen her in the evenings, when we've put the bin out or something... she will be standing there at her sink washing up and appears completely naked... definitely topless
We live across from her so can see in