gradientRect

def gradientRect(window, left_colour, right_colour, target_rect):
    """ Draw a horizontal-gradient filled rectangle covering <target_rect> """
    colour_rect = pg.Surface((2, 2))  # tiny! 2x2 bitmap
    pg.draw.line(colour_rect, left_colour, (0, 0), (0, 1))  # left colour line
    pg.draw.line(colour_rect, right_colour, (1, 0), (1, 1))  # right colour line
    colour_rect = pg.transform.smoothscale(colour_rect, (target_rect.width, target_rect.height))  # stretch!
    window.blit(colour_rect, target_rect)  # paint it