title: Update display all at one time PyGame
body: <p>Using PyGame, I get flickering things. Boxes, circles, text, it all flickers. I can reduce this by increasing the wait between my loop, but I though maybe I could eliminate it by drawing everything to screen at once, instead of doing everything individually. Here's a simple example of what happens to me:</p>
  
  <pre>
      import pygame, time
      pygame.init()
      screen = pygame.display.set_mode((400, 300))
      loop = "yes"
      while loop=="yes":
          screen.fill((0, 0, 0), (0, 0, 400, 300))
          font = pygame.font.SysFont("calibri",40)
          text = font.render("TextA", True,(255,255,255))
          screen.blit(text,(0,0))
          pygame.display.update()
  
          font = pygame.font.SysFont("calibri",20)
          text = font.render("Begin", True,(255,255,255))
          screen.blit(text,(50,50))
          pygame.display.update()
          time.sleep(0.1)
  </pre>
  
  <p>The "Begin" button flickers for me. It could just be my slower computer, but is there a way to reduce or eliminate the flickers? In more complex things I'm working on, it gets really bad. Thanks!</p>