Creating a freehand drawing program with a menu bar...

I'm trying to create a small application that allows me to draw freehand lines on a JPanel (which will reside in the Content Pane of a JFrame.  I also added a JMenuBar with a JMenu (containing a couple of JMenuItems) to the Root Pane using its setJMenuBar method.  

The problem is that if I don't call super.paintComponent(g) in the JPanel's paintComponent method, the background (red) doesn't get painted and there's a duplicate menubar painted on the Content Pane for some reason (?).  If I do call the super method, it repaints the background every time (which covers the duplicate menu bar but erases any previous lines that were drawn).  The call to super in paintComponent is commented out in the code below.



The code I've got so far is below:

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import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;


public class DrawTest
{


      /**
       *
       *  INNER class that represents the frame that contains the panel on which the drawing
       *  will be done (it is also the event listener).
       *
       */


    public class AFrame extends JFrame
    {

            private APanel mainPanel;
            private JMenuBar jmb;

        public AFrame()
        {

            super("DrawTest");
            setSize(500,500);
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                  // Create Menu Bar

                  jmb = new JMenuBar();
                  JMenu jm = new JMenu("Draw");
                  JMenuItem jmi_1 = new JMenuItem("Freehand");
                  JMenuItem jmi_2 = new JMenuItem("Rectangle");
                  jm.add(jmi_1);
                  jm.add(jmi_2);
                  jmb.add(jm);
                  getRootPane().setJMenuBar(jmb);


                  // Create the panel on which the drawing will be done

                  mainPanel = new APanel();
                  mainPanel.setBounds(0,0,500,500);
                  mainPanel.setBackground(Color.RED);
                  mainPanel.setVisible(true);
                  mainPanel.setOpaque(true);

                  getContentPane().setLayout(null);
                  getContentPane().add(mainPanel);


                  // Register the Panel/EventListener with itself

            mainPanel.addMouseMotionListener(mainPanel);
            mainPanel.addMouseListener(mainPanel);

        } // end AFrame constructor


        public void paint(Graphics g)
        {
                  super.paint(g);

        } // end paint






    } // end AFrame INNER class



      /**
       *
       *  INNER class that represents the single panel on which the drawing will actually
       *  be done.
       *
       */

      public class APanel extends JPanel implements MouseMotionListener, MouseListener
      {


            private Point mCurr;      // refers to the current point to which the line is to be drawn
            private Point mLast;      // refers to the last point that the line left off at


            public void paintComponent(Graphics g)
            {
                       
                  //super.paintComponent(g);
                  Graphics2D g2 = (Graphics2D) g;



                  // Ensure that both references have a legitimate instance

                  if (getLast() != null && getCurr() != null)
                  {

                        Line2D.Double line = new Line2D.Double(this.getLast(), this.getCurr());

                        g2.setPaint(Color.YELLOW);
                        g2.draw(line);

                        // Connect to the current point on the next event

                        setLast(getCurr());

                  }




            } // end paintComponent


            public void initializePanel()
            {
                  super.paintComponent(getGraphics());
            }



            // Get and set methods

            public void setCurr(Point p) {      mCurr = p; };
            public void setLast(Point p) {      mLast = p; };
            public Point getCurr() { return mCurr; };
            public Point getLast() { return mLast; };

            public void mouseReleased(MouseEvent e)
            {
                  this.setLast(null);
            }


            public void mouseDragged(MouseEvent e)
            {

                  // Set the panel's current point to the point at which this event occurred

                  this.setCurr(e.getPoint());

                  if (this.getLast() == null)
                        this.setLast(this.getCurr());

                  this.repaint();

            } // end mouseDragged


            // Unused method from MouseMotionListener Interface
            public void mouseMoved(MouseEvent e){};

            // Unused methods from the MouseListener Interface
            public void mousePressed(MouseEvent e){};
            public void mouseEntered(MouseEvent e){};
            public void mouseExited(MouseEvent e){};
        public void mouseClicked(MouseEvent e){};


      } // end APanel INNER class



      /**
       *
       *  Constructor of OUTER class that instantiates frame object of
       *  inner class <code>AFrame</code>.
       *
       */

    public DrawTest()
    {

          AFrame aframe = new AFrame();
        aframe.setVisible(true);

    } // end DrawTest constructor



    public static void main(String[] args)
    {

          DrawTest app = new DrawTest();

    } // end main




} // end DrawTest class

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I'm not sure if I'm going about things the right way or not.  Any ideas would be much appreciated.