Getting the "New" MenuItem to work.

Question

Posted this one in the Programming section before with no luck, maybe it will be easier to acquire an answer here considering I assume many here must have done this exact thing.
I have a GUI, in that GUI a selfmade Menu and mainarea is put. The Menu has a "New" option which is meant to replace the current mainarea with a new fresh one.
Simplified, the below describe what I got atm. I know it doesn't work and most likely cause lack of pointer-equivalent-code. Question is though, how can the Menu perform that task?
Any help greatly appreciated.
public class MyGui extends JFrame
     MyMenuBar menuBar;
     MyPanelWithStuff stuff;     
     public PaxGui()
          super();
          menuBar = new MyMenuBar(this);
          setJMenuBar(menuBar);
          buildStuff();
          pack();
          setVisible(true);
          // End of constructor PaxGui().
     public void buildStuff()
          stuff = new MyClassWithStuffExtendingPanel();
          getContentPane().add(stuff);
          // End of method buildStuff().
     // End of class MyGui extends JFrame.
public class MyMenuBar extends JMenuBar
     JMenu fileMenu;
     JMenuItem newMenuItem;
     ActionHandler actionHandler;
     MyGui myGui;
     public MyMenuBar (MyGui aMyGui)
          super();
          myGui = aMyGui;
          actionHandler = new ActionHandler();
          fileMenu = new JMenu("File");
          add(fileMenu);
          newMenuItem = new JMenuItem("New");
          fileMenu.add(newMenuItem);
          newMenuItem.addActionListener(actionHandler);
          // End of consrtuctor MyMenuBar().
     private class ActionHandler extends AbstractAction
          public void actionPerformed(ActionEvent aActionEvent)
               if (aActionEvent.getSource == newMenuItem)
                    {myGui.buildStuff();}                              
          // End of inner class ActionHandler extends AbstractAction.
// End of class MyMenuBar extends MenuBar.

Answer 1

It worked like a charm and just have a little follow
up. Both setVisible(true) and revalidate() work, so
which should one use and what is the difference.the (re)validate() goes up the chain of components and does layout and stuff (afaik). so if setVisible() works use that (it might trigger validate() anyway).
And Thanks alot for putting me back on track =).no problem ;)
thomas