CWnd.wndTopMost usage <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>