title: Get shown component in JScrollPane
body: <p>I have a JScrollPane containing a JPanel. I fill this JPanel with many buttons.</p>
  
  <p>Is there any possibility to get the currently shown buttons?</p>
  
  <p>I know I can access the children of a JPanel via <code>jpanel.getComponents()</code> but those are all components in this pane; I want only the ones that are currently on screen.</p>