docs: function (jax,state) {
        if (!jax.root.SRE.actionWidths) {
          MathJax.OutputJax[jax.outputJax].getMetrics(jax);
          try {this.computeActionWidths(jax)} catch (err) {
            if (!err.restart) throw err;
            return MathJax.Callback.After(["collapseState",this,state],err.restart);
          }
          state.changed = true;
        }
        return null;
      }