title: Can DirectDraw game access a backbuffer without locking it?
body: <p>I'm modding an old Windows DirectDraw game. I've created a DirectDraw proxy. It logs every IDirectDraw and IDirectDrawSurface call. The backbuffer looks like this <strong>after</strong> one <code>BltFast</code> call:</p>
  
  <p><img src="https://i.stack.imgur.com/fAoZK.png" alt="enter image description here"></p>
  
  <p>And like this <strong>before</strong> the next <code>BltFast</code> call:</p>
  
  <p><img src="https://i.stack.imgur.com/WBGks.png" alt="enter image description here"></p>
  
  <p>These pictures are dumped by <code>Lock</code>ing-copying-<code>Unlock</code>ing the backbuffer before and after any <code>BltFast</code> call.
  There are no other IDirectDraw(Surface) calls between these two <code>BltFast</code> calls, especially no <code>Lock</code>/<code>Unlock</code> calls. How is this possible?</p>