希望GWT中有一个面板来填充页面：

public class Main  implements EntryPoint
{
    public void onModuleLoad()
    {
        HorizontalSplitPanel split = new HorizontalSplitPanel();
        //split.setSize("250px", "500px");
        split.setSplitPosition("30%");

        DecoratorPanel dp = new DecoratorPanel();
        dp.setWidget(split);

        RootPanel.get().add(dp);
    }

}