title: What is the point of graphics context in xcb_copy_area?
body: <p>The function <code>xcb_copy_area</code> by my understanding essentially copies a region from one xcb_drawable to another. I'm not sure then why it would also take a graphics context as a parameter, seeing as the source of the copy has presumably already been drawn or rendered. What is the use of this parameter in this case?</p>
  
  <p>It's worth noting that my understanding of graphics contexts are not great but there aren't many resources on explaining them. I'm assuming this is an issue with my mental model of what's going on within xcb.</p>