对齐按钮中的 SWT 问题

Question

我编写了一个小程序，它有 2 个列表视图和一个用于选择和取消选择所选组合的按钮。问题是我无法将按钮与列的中心对齐。public static void main(String[] args) {    Display display = new Display();    Shell shell = new Shell(display);    shell.setLayout(new FillLayout());    shell.setLayout(new GridLayout(3, true));    GridData data = new GridData(GridData.FILL_BOTH);    // Creating Label    new Label(shell, SWT.NONE).setText("This is a plain Text");    new Label(shell, SWT.NONE).setText("");    new Label(shell, SWT.NONE).setText("This is a plain Text");    // Create a single-selection list    List single = new List(shell, SWT.BORDER | SWT.SINGLE | SWT.V_SCROLL);    single.setLayoutData(data);    // Add the items, one by one    for (int i = 0, n = ITEMS.length; i < n; i++) {        single.add(ITEMS[i]);    }    single.setSelection(0);    //////////////////////////////////////////////////////    // Button button1=new Button(shell, SWT.ARROW | SWT.RIGHT);    Group first = new Group(shell, SWT.CENTER);    first.setLayout(new RowLayout(SWT.VERTICAL));    Button button1 = new Button(first, SWT.NONE);    // GridData bdata = new GridData(GridData.HORIZONTAL_ALIGN_BEGINNING);    Button button3 = new Button(first, SWT.PUSH);    // button3.setLayoutData(bdata);    button1.setText("Select    ");    button3.setText("UnSelect");    //////////////////////////////////////////////    // Create a single-selection list    List single2 = new List(shell, SWT.BORDER | SWT.SINGLE | SWT.V_SCROLL);    single2.setLayoutData(data);    single2.add("");    single2.setSelection(0);    shell.open();    System.out.println(single.getItem(single.getSelectionIndex()));    while (!shell.isDisposed()) {        if (!display.readAndDispatch()) {            display.sleep();        }    }    display.dispose();}实际输出：预期输出：