See How to Write an Internal Frame Listener in The Java Tutorial and The Java Class Libraries (update) for further documentation.
Invoked when an internal frame is activated.seejavax.swing.JInternalFrame#setSelected
Invoked when an internal frame has been closed.seejavax.swing.JInternalFrame#setClosed
Invoked when an internal frame is in the process of being closed. The close operation can be overridden at this point.seejavax.swing.JInternalFrame#setDefaultCloseOperation
Invoked when an internal frame is de-activated.seejavax.swing.JInternalFrame#setSelected
Invoked when an internal frame is de-iconified.seejavax.swing.JInternalFrame#setIcon
Invoked when an internal frame is iconified.seejavax.swing.JInternalFrame#setIcon
Invoked when a internal frame has been opened.seejavax.swing.JInternalFrame#show