title: Change the height of a panel at runtime
body: <p>How to change the height of panel at runtime?</p>
  
  <p>I have some panels inside a <code>JFrame</code>, I tried on one of them:</p>
  
  <pre><code>int w = panel.getWidth();
  panel.setSize(w, 1000);
  </code></pre>
  
  <p>But there's no effect. What's wrong?</p>