Java GXT tree click

import java.io.Serializable;
import java.util.List;
import com.sencha.gxt.data.shared.TreeStore;
import com.sencha.gxt.data.shared.TreeStore.TreeNode;
public class BaseDto implements Serializable, TreeStore.TreeNode<BaseDto> {
private static final long serialVersionUID = 1L;
private Integer id;
private String name;
private String keyname;
protected BaseDto() {
}
public BaseDto(Integer id, String name, String keyname) {
this.id = id;
this.name = name;
this.keyname = keyname;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getKeyname() {
return keyname;
}
public void setKeyname(String keyname) {
this.keyname = keyname;
}
@Override
public BaseDto getData() {
return this;
}
@Override
public List<? extends TreeNode<BaseDto>> getChildren() {
return null;
}
@Override
public String toString() {
return name != null ? name : super.toString();
}
}

        SimpleSafeHtmlCell<String> cell = new SimpleSafeHtmlCell<String>(SimpleSafeHtmlRenderer.getInstance(), "click") {
@Override
public void onBrowserEvent(Context context, Element parent, String value, NativeEvent event,
ValueUpdater<String> valueUpdater) {
super.onBrowserEvent(context, parent, value, event, valueUpdater);
if ("click".equals(event.getType())) {
Info.display("Tıklama", "Tıklama yaptığınız seçenek \"" + value + "\"!");
AlertMessageBox messageBox = new AlertMessageBox("Tıklama", value);
messageBox.show();
}
}
};

          tree.getSelectionModel().setSelectionMode(SelectionMode.SINGLE);
tree.getSelectionModel().addSelectionHandler(new SelectionHandler<BaseDto>() {
@Override
public void onSelection(SelectionEvent<BaseDto> event) {
// TODO Auto-generated method stub
BaseDto mnu = event.getSelectedItem();
Info.display("Tree Handler", mnu.getKeyname());
}
}); 

          tree.getSelectionModel().addSelectionChangedHandler(new SelectionChangedEvent.SelectionChangedHandler<BaseDto>() {
@Override
public void onSelectionChanged(SelectionChangedEvent<BaseDto> event) {
List<BaseDto> mnus = event.getSelection();
Integer i = new Integer(0);
for (i=0; i<mnus.size();++i) {
Info.display("tree handler", mnus.get(i).getKeyname());
}
}
});