title: How do I get the size (width x height) of my pygame window
body: <p>I have created a window using</p>
  
  <pre><code>pygame.display.set_mode((width, height), 
                          pygame.OPENGL | pygame.DOUBLEBUF | pygame.RESIZABLE)
  </code></pre>
  
  <p>Later on in the app I want to be able to ask that window its width and height so I can decide how to process the mouse position.</p>
  
  <p>How do I access the dimensions of that pygame window elsewhere in the program? (event processing loop)</p>