title: CWnd.wndTopMost usage
body: <p>What CWnd.wndTopMost is used for?</p>
  
  <p>in definition I found that it is:</p>
  
  <pre><code>static AFX_DATA const CWnd wndTopMost;
  </code></pre>
  
  <p>How macro AFX_DATA affects this line?</p>
  
  <p>This code:</p>
  
  <pre><code>this-&gt;wndTopMost.SetWindowPos(NULL, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
  </code></pre>
  
  <p>Returns error</p>
  
  <pre><code>'CWnd::SetWindowPos' : cannot convert 'this' pointer from 'const CWnd' to 'CWnd &amp;'
  </code></pre>
  
  <p>Why does it needs reference? This method returns to nothing.</p>