title: How can I get access to a QMessageBox by QTest
body: <p>I am creating some automated <strong>GUI tests</strong> in my application using <strong>QTest</strong>.</p>
  
  <p>I can access the widgets from my application using the command:</p>
  
  <pre><code>savePushButton = mainWindow-&gt;findChild&lt;QPushButton *&gt;("savePushButton");
  </code></pre>
  
  <p>It is working fine, but now I have to click on the OK button of a <strong>QMessageBox</strong>.</p>
  
  <p>I created the <strong>QMessageBox</strong> in my application like this:</p>
  
  <pre><code>if( something_wrong )
  {
      QMessageBox::warning(new Widget(), "Title", "Something wrong!");
  }
  </code></pre>
  
  <p>How can I have access to this <strong>QMessageBox</strong>, and its buttons?</p>