code: public void unmark() {
      // check if it's marked before removing the style class
      if (marked) {
        preferencesGroup.getRenderer().removeStyleClass(MARKED_STYLE_CLASS);
        preferencesGroup.getRenderer().getTitleLabel().removeEventHandler(
            MouseEvent.MOUSE_EXITED, unmarker
        );
        marked = !marked;
      }
    }
docs: Unmarks this group in the GUI.
  Is used for the search, which marks and unmarks items depending on the match as a form of
  visual feedback.