def overlap(xl1, yl1, nx1, ny1, xl2, yl2, nx2, ny2):
    """
    Determines whether two windows overlap
    """
    return (xl2 < xl1 + nx1 and xl2 + nx2 > xl1 and yl2 < yl1 + ny1 and yl2 +
        ny2 > yl1)
