When you say "invoke another internal frame" what do you mean? Call some method on the other internal frame? Create another frame? Since you mention actionPerformed(), why not make the frame you want to "react" an ActionListener, and have it's actionPerformed() method call the method you want to call on this frame. In the "originator" frame, you could make an addActionListener() method that adds the specified ActionListener to whatever componenent is calling the actionPerformed() method in your question. Then whenever that component throws an action event, all ActionListeners attached in this way are notified...
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