title: Custom Java tool tip with Swing components as content does not show up
body: <p>I'm trying to show multiple images in a component's tooltip, found <code>createToolTip()</code> and implemented a custom that adds the needed components like this:</p>
  
  <pre><code>setComponent(component);
  
  JPanel images = new JPanel(null);
  images.setLayout(new BoxLayout(images, BoxLayout.X_AXIS));
  for(ImageIcon icon:myIcons) {
      images.add(new JLabel(icon));
  }
  
  JPanel content = new JPanel(new BorderLayout());
  content.add(new JLabel(title), BorderLayout.NORTH);
  content.add(new JLabel(description));
  content.add(images, BorderLayout.SOUTH);
  
  add(content);
  </code></pre>
  
  <p>However, all I see is a little dot, indicating that the tool tip is shown, but somehow the size is ignored. What do I miss implementing a custom tooltip?</p>