向复合布局添加滚动条在java swt中不起作用。

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ScrolledComposite;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

public class ScrollableCompositeExample {
    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new FillLayout());

        // 创建一个滚动容器
        ScrolledComposite scrolledComposite = new ScrolledComposite(shell, SWT.V_SCROLL | SWT.H_SCROLL);
        scrolledComposite.setExpandHorizontal(true);
        scrolledComposite.setExpandVertical(true);

        // 创建一个复合布局容器
        Composite composite = new Composite(scrolledComposite, SWT.NONE);
        composite.setLayout(new FillLayout());

        // 向复合布局容器添加组件
        for (int i = 0; i < 20; i++) {
            Label label = new Label(composite, SWT.NONE);
            label.setText("Label " + i);
        }

        // 设置复合布局容器的大小
        composite.setSize(composite.computeSize(SWT.DEFAULT, SWT.DEFAULT));

        // 将复合布局容器设置为滚动容器的内容
        scrolledComposite.setContent(composite);

        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
}