setSelectionAppearance(SelectionAppearance.CHECKBOX) for a grid

Hi All,

Just i want to get the state (true/false) of the header checkbox selection, if the grid SelectionAppearance.CHECKBOX is checked or unchecked.


listgrid.addSelectionUpdatedHandler(new SelectionUpdatedHandler() {
public void onSelectionUpdated(SelectionUpdatedEvent event) {

SC.say("isSelected status :- "+listgrid./--which method will return selectAll state--/);

}
});

which method i need to use to get state?