this.xcasWriteItem = new JMenuItem("Write XCAS File", KeyEvent.VK_W);
this.xcasWriteItem.addActionListener(new XCASSaveHandler(this));
this.fileMenu.add(this.xcasWriteItem);
this.fileMenu.addSeparator();
JMenuItem exit = new JMenuItem("Exit", KeyEvent.VK_X);
exit.addActionListener(new SystemExitHandler(this));
this.fileMenu.add(exit);
// Disable menu items that can't be executed yet.
this.typeSystemWriteItem.setEnabled(false);
setEnableCasFileReadingAndWriting();