title: JFrame.HIDE_ON_CLOSE onHide event?
body: <p>I have a <code>WorldEditor</code> JFrame that launches a <code>Game</code> JFrame. However, when the <code>Game</code> closes, I don't want it to end the entire program, so I set the default close operation to <code>HIDE_ON_CLOSE</code>. But, to save resources, I pause the <code>WorldEditor</code> while the <code>Game</code> is running.</p>
  
  <p>How can I detect when the <code>Game</code> window is hidden so I can resume <code>WorldEditor</code>?</p>