Select Children when selecting Parent checkbox - gwt

Question

I am using a Grid where the first column is checkbox. Every row is a folder which can have many other elements to be selected. There could be another folder inside a folder.
Now, when I have to select a element I have to select it one by one. I am not able to understand that how could I make it possible that if I check a folder checkbox, It checks the all selectable elements inside this folder.
Please let me know if more info required.
RemoteSortTreeLoader<BasicModel> loader =
new BaseRemoteSortTreeLoader<BasicModel>(proxy, reader) {
public boolean hasChildren(BasicModel parent) {
//code;
}
};
TreeStore store = new TreeStore(loader);
List<ColumnConfig> columnList = new ArrayList<ColumnConfig>();
CheckBoxSelectionModel checkBoxSelectionModel =
new CheckBoxSelectionModel();
columnList.add(checkBoxSelectionModel.getColumn());
ColumnModel columns = new ColumnModel(columnList);
EditorTreeGrid grid = new EditorTreeGrid<BasicModel>(store,columns);
grid.getSelectionModel().setSelectionMode(SelectionMode.SIMPLE);
grid.getSelectionModel().addListener(Events.BeforeSelect,
new Listener<SelectionEvent<BasicModel>>() {
#Override
public void handleEvent(SelectionEvent<BasicModel> event) {
if (event.getModel() instanceof SDPTimelineCatalogModel) {
event.setCancelled(false);
}
} // handleEvent
}
);
grid.getSelectionModel().addSelectionChangedListener(
new SelectionChangedListener<BasicModel>() {
#Override
public void selectionChanged(SelectionChangedEvent<BasicModel> event) {
logger.info(" Inside addSelectionChangedListener ");
if (event.getSelection().size() == 0) {
disableNext();
} else {
enableNext();
}
} // selectionChanged
}
);
thanks