title: gwt panel horizontal alignment not working
body: <p>I have a GWT dialog box that looks like the following:</p>
  
  <pre><code>public class FooDialog extends DialogBox {
  
  public FooDialog() {
          setText("Foo Dialog");
          VerticalPanel outer = new VerticalPanel();
          outer.setBorderWidth(3);
          outer.setSize("400px", "200px");
          outer.setHorizontalAlignment(HasAlignment.ALIGN_CENTER);
          outer.setVerticalAlignment(HasAlignment.ALIGN_MIDDLE);
  
          Button cancelButton = new Button("Cancel", new ClickHandler() {
        public void onClick(ClickEvent event) {
          hide();
        }
      });
  
          HorizontalPanel buttons = new HorizontalPanel();
          buttons.setBorderWidth(3);
          buttons.add(cancelButton);
  
          outer.add(buttons);
  
          setWidget(outer);
      }
  }
  </code></pre>
  
  <p>For some reason the 'buttons' panel does not obey the horizontalAlignment setting; it sticks to the left side of the outer panel. It does, however, obey the vertialAlignment setting. Any ideas? Thanks!</p>