public   static   void  main(String[] args) {
        Display display =  new  Display();
         final  Shell shell =  new  Shell(display);
        shell.setLayout( new  GridLayout());
         final  Composite composite1 =  new  Composite(shell, SWT.NONE);
        composite1.setLayout( new  RowLayout());
         final  Combo combo1 =  new  Combo(composite1, SWT.NONE);
        combo1.setToolTipText("combo1");
        combo1.setItems( new  String[]{"cb1_item1", "cb1_item2", "cb1_item3",
            "cb1_item4"});
        combo1.setLayoutData( new  RowData());
         final  Combo combo2 =  new  Combo(composite1, SWT.NONE);
        combo2.setToolTipText("combo2");
        combo2.setItems( new  String[]{"cb2_item1", "cb2_item2", "cb2_item3"});
        combo2.setLayoutData( new  RowData());
        Combo combo3 =  new  Combo(composite1, SWT.NONE);
        combo3.setToolTipText("combo3");
        combo3.setItems( new  String[]{"cb3_item1", "cb3_item2"});
        combo3.setLayoutData( new  RowData());

         final  Composite composite2 =  new  Composite(shell, SWT.NONE);
        composite2.setLayout( new  RowLayout());
        Button button1 =  new  Button(composite2, SWT.NONE);
        button1.setText("hide/show");
        button1.addSelectionListener( new  SelectionAdapter() {
             public   void  widgetSelected(SelectionEvent arg0) {
                 final  RowData layoutData = (RowData) combo2.getLayoutData();
                 if  (combo2.isVisible()) {
                    combo2.setVisible(false);
                    (layoutData).width =  0 ;
                    layoutData.exclude = true;
                    
                }  else  {
                    combo2.setVisible(true);
                    (layoutData).width = SWT. DEFAULT ;
                    layoutData.exclude = false;
                    
                }
                composite1.layout();
                shell.layout();
            }
        });
        Button button2 =  new  Button(composite2, SWT.NONE);
        button2.setText("select combo");
        button2.addSelectionListener( new  SelectionAdapter() {
             public   void  widgetSelected(SelectionEvent arg0) {
                combo1.select( 0 );
            }
        });
        shell.open();
         while  (!shell.isDisposed()) {
             if  (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }