title: QGuiApplication::primaryScreen() with multiple screens on mac
body: <p>I want to capture a screenshot in Qt:</p>
  
  <pre><code>originalPixmap = QPixmap();
      QScreen *screen = QGuiApplication::primaryScreen();
      if (screen) {
          originalPixmap = screen-&gt;grabWindow(0);
      }
  </code></pre>
  
  <p>That works usually fine. When I have a second monitor connected on a Mac, though, <code>grabWindow()</code> will return one image that shows both displays. Is there a way to just capture the screens individually?</p>