title: How to customize shadow
body: <p>I want to change the appearance of <code>QCompleter</code> popup window. I have tried <code>QGraphicsDropShadowEffect</code> but it's not working because that window has system shadow. And if I combine <code>DropShadowEffect</code> with the platform-dependent <code>WinApi</code> code to disable the system shadow widget, it does not show up at all.</p>
  
  <p>Disabling system shadow example:</p>
  
  <pre><code>&lt;!-- language: lang-cpp --&gt;
  HWND hWnd = reinterpret_cast&lt;HWND&gt;(popup()-&gt;winId());  
  DWORD windowStyle = GetClassLongW(hWnd, GCL_STYLE);          
  if(windowStyle &amp; CS_DROPSHADOW)                              
  {                                                            
      windowStyle ^= CS_DROPSHADOW;                            
      SetClassLongW(hWnd, GCL_STYLE, windowStyle);             
  }                        
  </code></pre>
  
  <p>Qt 5.0.1 <br/>
  gcc 4.7.2 <br/>
  Windows 7 x64 <br/></p>