title: Pygame Moving a box results in increment of size of box
body: <p>Initially there is a box,I want to move the box by increment or decrease in position of the box.What I get is it looks like object is scaling right or left.I am using pycharm and python 3.5.</p>
  
  <pre><code>__author__ = 'GK'
  import pygame
  
  green = (0,255,0)
  black = (0,0,0)
  pygame.init()
  GameDisplay=pygame.display.set_mode((800,600))
  pygame.display.set_caption("Momo Killer")
  x= False
  lead_x = 300
  lead_y = 300
  
  while x is False:
  for event in pygame.event.get():
      if event.type == pygame.QUIT:
        quit()
  
  
      if event.type == pygame.KEYDOWN:
          if event.key == pygame.K_LEFT:
              lead_x -= 20
          if event.key == pygame.K_RIGHT:
              lead_x += 20
  
  pygame.draw.rect(GameDisplay,green,[lead_x,lead_y,20,20])
  pygame.display.update()
  
  pygame.quit()
  quit()
  </code></pre>
  
  <p>By using the above code I get this(Shown in pic).</p>
  
  <p><img src="https://i.stack.imgur.com/7KrwP.png" alt="Output when using code"></p>