Hi, i am new with GXT, i usually do my projects in GWT, but i pick GXT for a new project and i having a little issue with a grid.

I am adding a checkbox selection model to my grid, works fine, but when my app load, the header of the checkbox column is "selected" and the checkbox doesn't show, works fine, even in i didn´t see the checkbox if i click the header all my rows selected, but my users don't like that they can't see the checkbox...

hope somebody can help me (and sorry for my bad english, im from mexico)

My code:

FlowLayout layout = new FlowLayout(10);
setLayout(layout);

RpcProxy<PagingLoadResult<DesbSuc>> proxy = new RpcProxy<PagingLoadResult<DesbSuc>>() {
@Override
protected void load(Object loadConfig, AsyncCallback<PagingLoadResult<DesbSuc>> callback) {
try {
service.getSucursalesBloqueadas((PagingLoadConfig) loadConfig, callback);
}
catch(Exception e) {
System.out.println("Error al cargar sucursales bloqueadas [GWT/client.view, DesbloqueoSucursal.java]");
}
}
};

final PagingLoader<PagingLoadResult<ModelData>> loader = new BasePagingLoader<PagingLoadResult<ModelData>>(proxy);

ListStore<DesbSuc> store = new ListStore<DesbSuc>(loader);

final PagingToolBar toolBar = new PagingToolBar(totPags);
toolBar.bind(loader);

List<ColumnConfig> configs = new ArrayList<ColumnConfig>();

CheckBoxSelectionModel<DesbSuc> sm = new CheckBoxSelectionModel<DesbSuc>();
sm.getColumn().setSortable(false);
sm.getColumn().setMenuDisabled(true);

configs.add(sm.getColumn());

ColumnConfig column = new ColumnConfig();
column.setId("paisBloqueado");
column.setHeader("Pais Bloqueado");
column.setMenuDisabled(true);
column.setSortable(false);
column.setWidth(100);
configs.add(column);

column = new ColumnConfig();
column.setId("canalBloqueado");
column.setHeader("Canal Bloqueado");
column.setMenuDisabled(true);
column.setSortable(false);
column.setWidth(100);
configs.add(column);

column = new ColumnConfig();
column.setId("sucursalBloqueada");
column.setHeader("Sucursal Bloqueada");
column.setMenuDisabled(true);
column.setWidth(120);
configs.add(column);

column = new ColumnConfig();
column.setId("fechaBloqueo");
column.setHeader("Fecha de Bloqueo");
column.setMenuDisabled(true);
column.setSortable(false);
column.setWidth(130);
configs.add(column);

column = new ColumnConfig();
column.setId("idRow");
column.setHeader("IDROW");
column.setMenuDisabled(true);
column.setSortable(false);
configs.add(column);

ColumnModel cm = new ColumnModel(configs);

final Grid<DesbSuc> grid = new Grid<DesbSuc>(store, cm);
grid.setStateId("desbloquedoSucursales");
grid.setSelectionModel(sm);
grid.addPlugin(sm);
grid.setLoadMask(true);
grid.setBorders(true);
grid.setAutoExpandColumn("idRow");

grid.addListener(Events.Attach, new Listener<GridEvent<DesbSuc>>() {
public void handleEvent(GridEvent<DesbSuc> be) {
PagingLoadConfig config = new BasePagingLoadConfig();
config.setOffset(0);
config.setLimit(totPags);

loader.load(config);
}
});

Button btn = new Button();
btn.setText("Liberar sucursal(es)");
btn.setIconStyle("accept16");

ToolBar toolBarGrid = new ToolBar();
toolBarGrid.add(btn);

ContentPanel cp = new ContentPanel();
cp.setHeading("Desbloqueo de Sucursal(es)");
cp.setIconStyle("house_go_gray16");
cp.setFrame(true);
cp.setLayout(new FitLayout());
cp.setSize(900, 400);

cp.setBottomComponent(toolBarGrid);
cp.setTopComponent(toolBar);
cp.add(grid);

add(cp);