title: Using ModifyStyle with WS_THICKFRAME on a CPropertySheet/CDialog
body: <p>I have a CPropertySheet. </p>
  
  <p>When I use </p>
  
  <pre><code>ModifyStyle(DS_MODALFRAME, WS_POPUP | WS_THICKFRAME | WS_MAXIMIZEBOX);
  </code></pre>
  
  <p>inside an OnCreate handler everything is fine. The created window behaves as expected and is resizable.</p>
  
  <p>When I use the same code, just a tick later in CPropertySheet::OnInitDialog than this code has only the effect that the correct frame is shown, also the cursor changes when I drag over the window border. But there is no resize feature.</p>
  
  <p>Same happens for a CDialog when uses in OnInitDialog. Seams that some flags can't be changed after a window is created.</p>
  
  <p>Is there more information about this problem?</p>