如何确定GridBagLayout的行列啊

请各位帮我看看这个程序，为什么结果是这个样子的呢，我觉得应该是两行啊
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class GB extends Applet implements ItemListener
{
String msg="";
Checkbox Win98,winNT,solaris,mac;

public void init()
{
setBackground(Color.cyan);

GridBagLayout gbag=new GridBagLayout();
GridBagConstraints gbc=new GridBagConstraints();
setLayout(gbag);

Win98=new Checkbox("Windows 98",null,true);
winNT=new Checkbox("Windows NT/2000");
solaris=new Checkbox("Solaris");
mac=new Checkbox("MacOS");

gbc.weightx=1.0;
gbc.ipadx=200;
gbc.insets=new Insets(4,4,0,0);
gbc.anchor=GridBagConstraints.NORTHEAST;
gbc.gridwidth=GridBagConstraints.RELATIVE;
gbag.setConstraints(Win98,gbc);

gbc.gridwidth=GridBagConstraints.REMAINDER;
gbag.setConstraints(winNT,gbc);


gbc.gridwidth=GridBagConstraints.REMAINDER;
gbag.setConstraints(solaris,gbc);

gbc.weighty=1.0;
gbc.gridwidth=GridBagConstraints.RELATIVE;
gbag.setConstraints(mac,gbc);

add(Win98);
add(winNT);
add(solaris);
add(mac);

Win98.addItemListener(this);
winNT.addItemListener(this);
solaris.addItemListener(this);
mac.addItemListener(this);
}

public void itemStateChanged(ItemEvent ie)
{repaint();}

public void paint(Graphics g)
{
msg="Current state:";
g.drawString(msg,6,80);
msg="Windows 98: "+Win98.getState();
g.drawString(msg,6,100);
msg="Windows NT/2000: "+winNT.getState();
g.drawString(msg,6,120);
msg="Solaris: "+solaris.getState();
g.drawString(msg,6,140);
msg="MacOS: "+mac.getState();
g.drawString(msg,6,160);
}
}