title: (Qt) two rows of widgets in a toolbar
body: <p>I can't figure out how creating a toolbar with two rows of widgets. I'm working on a Python3/Qt4 project.</p>
  
  <p>My guess :</p>
  
  <ul>
  <li><p>add a widget to the toolbar widget</p></li>
  <li><p>add a vertical layout (or a QGridLayout, it doesn't matter) to the widget</p></li>
  <li><p>add the toolbar's buttons to the layout</p></li>
  </ul>
  
  <p>But all I get is a tiny and empty toolbar : do I need to somehow 'stretch' the widget ?</p>
  
  <p>My Python3 code, trying to insert vertically two buttons in the toolbar :</p>
  
  <pre><code>    self.main_toolbar = self.addToolBar('MyToolBar')
  
      self.toolbar_widget = QtGui.QWidget(self.main_toolbar)
      self.toolbar_layout = QtGui.QVBoxLayout()
      self.toolbar_widget.setLayout(self.toolbar_layout)
  
      button1 = QtGui.QPushButton(self)
      button1.setText("button1")
      self.toolbar_layout.addWidget( button1 )
  
      button2 = QtGui.QPushButton(self)
      button2.setText("button2")
      self.toolbar_layout.addWidget( button2 )
  </code></pre>