title: pygame - updating score box
body: <p>I'm learning to use pygame and I have some problems with rendering text.</p>
  
  <p>The simplified code I'm working with is like this:</p>
  
  <pre><code>import pygame
  
  sizex =200; sizey =200
  
  pygame.init()
  clock = pygame.time.Clock()
  screen = pygame.display.set_mode((sizex,sizey))
  myfont = pygame.font.Font(None, 32)
  
  score=pygame.Rect(100,100,100,50)
  
  screen.fill((255,255,255))
  pygame.draw.rect(screen, (0,250,0), (10,10,10,10), 2)
  pygame.display.update()
  
  for i in xrange(0,1000): 
      msElapsed = clock.tick(2)
      text="I = %d" %i
      label = myfont.render(text, 1, (0,0,250))
      screen.blit(label, (100, 100))
  
      pygame.display.update(score)
  </code></pre>
  
  <p>I want update only the part of screen which contains the textbox. But this code is not doing this. The texts overwrite themselves and become unreadable after a while.</p>
  
  <p>What am I doing wrong?</p>