Per quanto riguarda il menu ho provato setFont ma vale solo per le voci del menu, io devo cambiare proprio la scritta "file".
Io ho usato:
Menu menuFile = new Menu("File");
Per quanto riguarda il problema di allargare la finestra, questo è il mio codice...
	codice:
	package jcshell.gui;
/*
 * This class create a dialog box for choice a font, size and style.
 * 
 * */
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class FontChooser extends JComponent{
  private JComboBox fontNameBox;
  private JComboBox fontSizeBox;
  
  private JComboBox fontStyleBox;/**/
 public JTextArea example;
  
  public FontChooser() {
    fontNameBox = new JComboBox();
    fontSizeBox = new JComboBox();
    fontStyleBox = new JComboBox();/**/
    example=new JTextArea("Your Text");
    String[] fonts = GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames();
    for ( int i = 0; i < fonts.length; i++)
    	fontNameBox.addItem(fonts[i]);
    for ( int i = 10; i < 40; i++)
      fontSizeBox.addItem(new Integer(i));
    fontStyleBox.addItem("Normal");
    fontStyleBox.addItem("Bold");
    fontStyleBox.addItem("Italic");
    fontStyleBox.setSelectedItem(Font.PLAIN);    
    fontSizeBox.setSelectedIndex(12);
    setLayout(new GridLayout());
    JPanel comboBoxPanel = new JPanel();
    comboBoxPanel.add(fontNameBox);
    comboBoxPanel.add(fontSizeBox);
    comboBoxPanel.add(fontStyleBox);   
    add(comboBoxPanel);
 
    JPanel TextPanel = new JPanel();
    TextPanel.add(example);
    add(TextPanel);
    setBorder(BorderFactory.createTitledBorder("Font"));
    ActionListener eventForwarder = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
    	 final int style;
    	    if(fontStyleBox.getSelectedItem()=="Italic")
    			style = Font.ITALIC;
    			else if(fontStyleBox.getSelectedItem()=="Bold")
    				style = Font.BOLD;
    			else style=Font.PLAIN;
       setFont(new Font((String)fontNameBox.getSelectedItem(), style, ((Integer)fontSizeBox.getSelectedItem()).intValue()));
        Font unfont = new Font((String)fontNameBox.getSelectedItem(), style, ((Integer)fontSizeBox.getSelectedItem()).intValue());
	    example.setFont(unfont);
      }
    };
    fontNameBox.addActionListener(eventForwarder);
    fontSizeBox.addActionListener(eventForwarder);
    fontStyleBox.addActionListener(eventForwarder);
  }
  public void setFont(Font f) {
    super.setFont(f);
    // Questa chiamata genera un PropertyChangeEvent
    fontNameBox.setSelectedItem(f.getName());
    fontSizeBox.setSelectedItem(new Integer(f.getSize()));
    fontStyleBox.setSelectedItem(f.getName());
    example.setFont(f);
  }
  public static Font showFontChooser(Component parent, String title, Font initialFont) {
	  FontChooser fc = new FontChooser();
    fc.setFont(initialFont);
    int answer = JOptionPane.showConfirmDialog(parent, fc, title, JOptionPane.OK_CANCEL_OPTION);
    if ( answer != JOptionPane.OK_OPTION )
    	return null;
    
    else{
      return fc.getFont();
    }
  }
}