private void DragSourceContainer_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { mouseDownCoordinates = Coordinates(e); if (DragManager.DragCandidate == null) { DragManager.DragCandidate = DragSource.GetElementToDrag(mouseDownCoordinates); if (DragManager.DragCandidate != null) { DragManager.DragCandidateSponsor = DragSource; } } }