skæve checkboxes

Hvorfor står disse checkboxe skævt iforhold til hianden.

er det muligt at lave checkboxgrupper med swing

Kode



import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.*;

import java.awt.Checkbox;
import java.awt.CheckboxGroup;


public class GUI extends javax.swing.JFrame    {
private GridBagLayout mainMenu;
private GridBagConstraints con;
private JPanel panel1,panel2;
private Checkbox c1,c2,c3,c4, c5, c6,c7,c8,c9,c10,c11;
private CheckboxGroup cbg;
private JButton b;

public GUI()  {
 
 
  setSize(1000, 800);
  mainMenu = new GridBagLayout();
  getContentPane().setLayout(mainMenu);
  panel1 = new JPanel();

  panel1.setLayout( new GridBagLayout());
 
 


 
 
 
  c1 = new Checkbox(\"e\");
 
  con = createGBC(0,0,1,1);
   
  panel1.add(c1, con);
 
  c2 = new Checkbox(\"f\");
  con = createGBC(0,1,1,1);
   
  panel1.add(c2, con);
 
  c3 = new Checkbox(\"f#\");
  con = createGBC(0,2,1,1);
  panel1.add(c3, con);
 
  c4 = new Checkbox(\"g\");
  con = createGBC(0,3,1,1);
  panel1.add(c4, con);
 
  c5 = new Checkbox(\"g\");
  con = createGBC(1,0,1,1);
  panel1.add(c5, con);
 
 
  c6 = new Checkbox(\"g\");
  con = createGBC(1,1,1,1);
  panel1.add(c6, con);
 
  c7 = new Checkbox(\"g\");
  con = createGBC(1,2,1,1);
  panel1.add(c7, con);
 
 
 
  panel1.setBorder( new TitledBorder(new EtchedBorder(EtchedBorder.LOWERED), \"Søg\" ));
            con = createGBC(0,0,1,1);
        getContentPane().add( panel1,con );
 



}






private GridBagConstraints createGBC(int x, int y, int width, int height)
    {
        GridBagConstraints gbc = new GridBagConstraints();
       
        gbc.gridx=x;
        gbc.gridy=y;
        gbc.gridwidth=width;
        gbc.gridheight= height;
       
        gbc.insets= new Insets(0,0,0,0);
       
        return gbc;
    }
   
    private void add(JComponent c, GridBagConstraints gbc)
    {
        //mainMenu.setConstraints(c, gbc);
        getContentPane().add(c);
    }
}