code: public static void bindDown (final Value<Boolean> value, final ToggleButton toggle)
      {
          toggle.addClickHandler(new ClickHandler() {
              public void onClick (ClickEvent event) {
                  value.updateIf(toggle.isDown());
              }
          });
          value.addListenerAndTrigger(new Value.Listener<Boolean>() {
              public void valueChanged (Boolean value) {
                  toggle.setDown(value);
              }
          });
      }
docs: Binds the specified toggle button to the supplied boolean value. The binding will work both
  ways: interactive changes to the toggle button will update the value and changes to the
  value will update the state of the toggle button.