If so, this is probably a result of water collecting on the sill plates and dripping slowly down the stucco... What condition are the sills in??? They may also have water damage... This would indicate the high probability that there is some structiral damage in the framing to the jacks on either side of the window as well as the framing undeer the window... In that case, the stucco would have to be removed, the window framing rebuilt and the wire mesh reinstalled and stucco reapplied... Very costly...