private void txtCoord_TextChanged(object sender, EventArgs e)
        {
            var coord = GeoUtil.ParseCoordinate(txtCoord.Text);

            if (coord != null)
            {
                foreach (var s in _streets)
                {
                    s.Distance = s.Coordinate != null?GeoUtil.Distance(coord, s.Coordinate) : -1;
                }
            }
            Refresh();
        }