code: public void showPreview(int buttonLeft) {
  
          UrlBuilder location = Window.Location.createUrlBuilder();
          location.setParameter(CmsGwtConstants.PARAM_DISABLE_DIRECT_EDIT, Boolean.toString(true));
          location.setParameter(CmsGwtConstants.PARAM_BUTTON_LEFT, Integer.toString(buttonLeft));
          Window.Location.assign(location.buildString());
      }
docs: Toggles the tool-bars visibility.<p>
  
  @param buttonLeft the selection button absolute left position, needed to show the leave preview button in the same location