** first row is consisted of : 3 JComboboxes.
** second row of one JTextArea
** third row of 3 buttons.

JPanel datePanel = new JPanel(new GridLayout(1,3,0,0));
String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" };
JComboBox petList = new JComboBox( petStrings );
JComboBox petList2 = new JComboBox( petStrings );
JComboBox petList3 = new JComboBox( petStrings );
datePanel.add( petList );
datePanel.add( petList2 );
datePanel.add( petList3 );
mainFrame.add( datePanel );

JPanel controlPanel = new JPanel();
controlPanel.setLayout(new FlowLayout());
final JTextArea commentTextArea = new JTextArea("",7,25);
JScrollPane scrollPane = new JScrollPane(commentTextArea);
controlPanel.add(scrollPane);
mainFrame.add(controlPanel);

JPanel buttonsPanel = new JPanel( new GridLayout(0,1,10,10) );
buttonsPanel.add( new JButton("x") );
buttonsPanel.add( new JButton("y") );
buttonsPanel.add( new JButton("z") );

mainFrame.add( buttonsPanel );