Strange rendering Python Pygame

import os
import lzma, base64
from random import randint
from pygame import Rect
from pygame import Vector2
import pygame

# graphics engine
class graphics:
    def __init__(s, resolution, windowScale):
        s.windowScale = windowScale
        s.scale = windowScale
        s.res = Vector2(resolution)
        s.winRes = s.res * s.scale
        s.setResVars()

        s.sprites = {}
        s.updates = []
        s.unblits = []

        s.fullscreenFlags = pygame.FULLSCREEN | pygame.SCALED | pygame.HWACCEL | pygame.HWSURFACE | pygame.DOUBLEBUF
        pygame.init()
        pygame.mouse.set_visible(False)
        s.primary = pygame.display.set_mode((int(s.winRes[0]), int(s.winRes[1])))
        s.primary.set_alpha(None)

    def setResVars(s):
        s.center = (s.res[0] // 2, s.res[1] // 2)
        s.w = s.res[0]
        s.h = s.res[1]
        s.midTop = (s.center[0], 0)
        s.midBottom = (s.center[0], s.res[1])
        s.midLeft = (0, s.center[1])
        s.midRight = (s.res[0], s.center[1])

    def makeUnblit(s):
        surface = pygame.Surface(s.updates[-1][1])
        surface.blit(s.primary, (0, 0), s.updates[-1])
        s.unblits += [s.behind(surface, s.updates[-1])]

    def unblit(s):
        while s.unblits:
            unblit = s.unblits.pop()
            s.updates += [unblit.r]
            s.primary.blit(unblit.surface, unblit.r[0])

    def update(s):
        pygame.display.update(s.updates)
        s.updates = []
        s.unblit()

    def flush(s):
        s.updates = []
        pygame.display.update()

    def mouse(s):
        mp = pygame.mouse.get_pos()
        return (mp[0] // s.scale, mp[1] // s.scale)

    def loadSprite(s, id, filename, dimensions=(1, 1), colorkey=None):
        surface = pygame.image.load(filename).convert()
        sw, sh = Vector2(surface.get_rect().size) * s.scale
        w, h = (int(sw / dimensions[0]), int(sh / dimensions[1]))
        newSurface = pygame.transform.scale(surface, (int(sw), int(sh)))
        newSurface.set_colorkey(colorkey)
        s.sprites[id] = [newSurface.subsurface(((index % dimensions[0] * w, index // dimensions[0] * h), (w, h))) for index in range(dimensions[0] * dimensions[1])]

    def sw(s, id):
        return s.sprites[id][0].get_rect().w

    def sh(s, id):
        return s.sprites[id][0].get_rect().h

    def cx(s, id):
        return s.sprites[id][0].get_rect().center[0]

    def cy(s, id):
        return s.sprites[id][0].get_rect().center[1]

    def blit(s, id, xy, index=0, center=False, unblit=False):
        a = Vector2(xy) * s.scale
        b = s.sprites[id][0].get_rect()
        a -= b.center if center else (0, 0)
        s.updates += [(a, b.size)]
        if unblit:
            s.makeUnblit()
        s.primary.blit(s.sprites[id][index], a)

    def rect(s, color, xy, wh, lineThickness=0, unblit=False):
        r = (Vector2(xy) * s.scale, Vector2(wh) * s.scale)
        pygame.draw.rect(s.primary, color, r, lineThickness)
        s.updates += [r]

    class behind:
        def __init__(s, surface, r):
            s.surface = surface
            s.r = r

# if more than 100 updates, update the whole screen
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (128, 0, 0)

IMAGE_CROSSHAIR = b'/Td6WFoAAATm1rRGAgAhARYAAAB0L+Wj4ACXAJJdAESUBcR6J/b37omOUJCIs6rVUCaEMRn335INOFFYHloaVPVi8u5\
fWYmItWESIqUBzMmpnnr19bxep/TDJOFgavLr4xVaRkaNk1ElcJQYsossarUihOK/muXes2ISsz9VnoA0A+BIQ17APXpBlHeawXuKT7OAaemEpc\
PWcIXUVjZ1PuesTr2gLw7N9ycZK/OQveAAAAAASgLlBJyi5PgAAa4BmAEAAI8uFaSxxGf7AgAAAAAEWVo='

# DON'T PANIC!!! this saves the crosshair image to disk
if not os.path.isfile("crosshair.png"):
    print("Creating crosshair image...", end="")
    data = lzma.decompress(base64.b64decode(IMAGE_CROSSHAIR))
    fh = open("crosshair.png", "wb")
    fh.write(data)
    fh.close()
    print("Done!")

GRAPH = graphics((512, 360), 2)
GRAPH.loadSprite("crosshair", "crosshair.png", colorkey=BLACK)

# draw a load of red circles to the primary display
for i in range(200):
    pygame.draw.circle(GRAPH.primary, RED, (randint(0, 1024), randint(0, 720)), 25)
pygame.display.update()

exit = False
while not exit:
    events = pygame.event.get()
    for event in events:
        if event.type == pygame.QUIT or (event.type == pygame.KEYUP and event.key == pygame.K_ESCAPE):
            exit = True
        elif event.type == pygame.KEYUP and event.key == pygame.K_F5:
            pass

        GRAPH.blit("crosshair", GRAPH.mouse(), center=True, unblit=True)
        GRAPH.update()

pygame.quit()