GXT4.0 BorderLayoutContainer布局

@Override
public void onModuleLoad() {

BorderLayoutContainer con = new BorderLayoutContainer();

ContentPanel cp = new ContentPanel();
cp.setHeading("North");
cp.add(new Label("North Content"));
BorderLayoutData d = new BorderLayoutData(.20);
d.setMargins(new Margins(5));
d.setCollapsible(true);
d.setSplit(true);
con.setNorthWidget(cp, d);

cp = new ContentPanel();
cp.setHeading("West");
cp.add(new Label("West Content"));
d = new BorderLayoutData(.20);
d.setMargins(new Margins(0, 5, 5, 5));
d.setCollapsible(true);
d.setSplit(true);
d.setCollapseMini(true);
con.setWestWidget(cp, d);

cp = new ContentPanel();
cp.setHeading("Center");
cp.add(new Label("Center Content"));
d = new BorderLayoutData();
d.setMargins(new Margins(0, 5, 5, 0));
con.setCenterWidget(cp, d);

Viewport v = new Viewport();
v.add(con);
RootPanel.get().add(v);

}