title: Qt: Style the >> arrow when a QToolBar is too small
body: <p>I have a QToolBar with <strong>QToolButtons</strong>. When the main window is too small, it will show a ">>" button , to extend the view into multiple lines and show all QToolButtons.</p>
  
  <p><strong>How can I style this ">>" button?</strong> I'd like to change the icon and the background color.</p>
  
  <p>I already tried with these selectors: QToolButton::menu-indicator, QToolButton::menu-button, QToolButton::down-arrow. Doesn't work.</p>
  
  <p>How can I change the color and the width of the ">>" button?</p>
  
  <pre><code>QToolButton {
      background-color: transparent;
      border: 1px solid #3A3939;
      border-radius: 3px;
  }
  
  QToolButton:hover, QToolButton::menu-button:hover {
      background: #787876;
  }
  
  QToolButton::checked{
      background: #484846;
      border: 1px solid #787876;
  }
  
  QToolButton:pressed, QToolButton::menu-button:pressed {
      background: #787876;
  }
  
  QToolButton[popupMode="1"]{
  /* only for MenuButtonPopup */
      padding-right: 30px;
      background: red;
  }
  QToolButton[popupMode="2"]{
  /* only for OSC Server Status */
      padding-right: 30px;
      background: #484846;
  }
  QToolButton[popupMode="2"]:hover{
      background: #787876;
  }
  QToolButton::down-arrow{
  } 
  /* the subcontrols below are used only in the MenuButtonPopup mode */
  QToolButton::menu-button{
  }
  
  QToolButton::menu-button:hover{
      background: #787876;
  }
  QToolButton::menu-button:pressed{
  }
  QToolButton::menu-indicator{
      bottom: 5px;
      right: 5px;
  }
  </code></pre>