title: How to disable JSplitPane arrow button
body: <p><p>
  How do I disable(grey-out) the arrow button on the JSplitPane. I do know how to get the button from BasicSplitPaneDivider like this:</p>
  
  <pre>
  final int UP_ARROW = 0;
  final BasicSplitPaneUI ui = (BasicSplitPaneUI) splitPane.getUI();
  final BasicSplitPaneDivider divider = ui.getDivider();
  final JButton upArrowButton = (JButton) divider.getComponent(UP_ARROW);
  </pre>
  
  <p>, but when I try <code>upArrowButton.setEnabled(false)</code>, it doesn't grey-out the up arrow, but does disable it. I want the user to have a visual feedback that the up arrow button is disabled. I did try <code>upArrowButton.getAction().setEnabled(false)</code>, but it doesn't work(NullPointerException).<p>
  Please help</p>