title: Call glewInit once for each rendering context? or exactly once for the whole app?
body: <p>I have a question about how to (correctly) use <code>glewInit()</code>.</p>
  
  <p>Assume I have an multiple-window application, should I call <code>glewInit()</code> exactly once at application (i.e., global) level? or call <code>glewInit()</code> for each window (i.e., each <code>OpenGL</code> rendering context)?</p>