Provides Listener for different Graphical User Interface objects.

{@link dguitar.gui.DGuitar DGuitar}, has a DestktopPane that contains JInternalFrames that can be PieceInternalFrames or MidiInternalFrames.

PieceInternalFrames contain a single PiecePanel that contains many TrackPanel.

TrackPanel may cotain one or more BarPanel that contain different Bars.

MidiInternalFrames are used to display and play the MIDI files.

## Related Documentation

None at this moment. @see dguitar.gui.DGuitar