title: matplotlib.backends.backend_qt5 vs from matplotlib.backends.backend_qt5agg
body: <p>What is the difference between </p>
  
  <p><code>matplotlib.backends.backend_qt5</code></p>
  
  <p>and </p>
  
  <p><code>matplotlib.backends.backend_qt5agg</code>?</p>
  
  <p>It seems like they have somethings in common.</p>
  
  <p>For example,</p>
  
  <pre><code>from matplotlib.backends.backend_qt5 import NavigationToolbar2QT as Navi_qt5
  </code></pre>
  
  <p>and</p>
  
  <pre><code>from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as Navi_qt5agg
  </code></pre>
  
  <p>import the same method as shown by using </p>
  
  <pre><code>id(Navi_qt5)
  </code></pre>
  
  <p>and</p>
  
  <pre><code>id(Navi_qt5agg)
  </code></pre>