title: How to add a scrollbar to a Qcombobox
body: <p>I use python, and qt5, and qt designer. I want to add a scroll bar to the combo box. Any way to add a scrollbar using style-sheet? Other ways are also good.</p>
  
  <p>This is the style-sheet currently used in the combo box.</p>
  
  <pre><code>QComboBox { 
      combobox-popup: 0;
  }
  </code></pre>
  
  <p>I use this because I want to show the drop down list in 10 order.
  There seems to be no more data below because there are no scrollbars at this time.</p>
  
  <p>If you know how, Please help me.</p>
  
  <p>This is the situation now:</p>
  
  <p><img src="https://i.stack.imgur.com/fUJLK.jpg" alt=""></p>
  
  <p>But I want:</p>
  
  <p><img src="https://i.stack.imgur.com/ThkzQ.jpg" alt=""></p>