Make Window its own ActionListener
Make Window its own ActionListener

And add ActionCommand to every active menu item, so we can tell the
sources appart with just one listener.
Team-Machu-Picchu/Java-Basics-Teamwork-Assignment,FilipFilipov/Java-Slide-Puzzle,FilipFilipov/Java-Slide-Puzzle,Team-Machu-Picchu/Java-Basics-Teamwork-Assignment