title: JScrollPane doesn't work with JList
body: <p>I have a <code>JList</code> with a <code>DefaultListModel</code> and a <code>JScrollPane</code> for vertical scrolling in it:</p>
  
  <pre><code>private DefaultListModel&lt;DMatrixSet&gt; drawingsModel = new DefaultListModel&lt;&gt;();
  private JList&lt;DMatrixSet&gt; drawings = new JList&lt;&gt;();
  private JScrollPane scrollPane = new JScrollPane();
  </code></pre>
  
  <p>This is how I set them up:</p>
  
  <pre><code>    drawings.setBounds(30 + ENTRY_WIDTH, 40 + 10, ENTRY_WIDTH, ENTRY_HEIGHT);
  
      getContentPane().add(scrollPane);
  
      scrollPane.setBounds(30 + ENTRY_WIDTH*2, 40 + 10, 15, ENTRY_HEIGHT);
      scrollPane.getViewport().add(drawings);
  
      drawings.setModel(drawingsModel);
  </code></pre>
  
  <p>The problem is: the scroll pane simply does not work. It can't be scrolled nor somehow used. I add 30 elements to the list after init:</p>
  
  <pre><code>    for (int i = 0; i &lt; 30; i++)
          drawingsModel.addElement
      (new DMatrixSet("test" + i, 1, 1));
  </code></pre>
  
  <p>And this is what I can see:</p>
  
  <p><img src="https://sc.reflex.rip/VoGWSA.png" alt="sc001"></p>
  
  <p>I cannot scroll nor somehow interact with the scroll pane, and can so can only see the first 14 elements of the list.</p>