code: function _execCommand(doc, command, nodeName, className) {
      if (className) {
        var eventListener = dom.observe(doc, "DOMNodeInserted", function(event) {
          var target = event.target,
              displayStyle;
          if (target.nodeType !== wysihtml5.ELEMENT_NODE) {
            return;
          }
          displayStyle = dom.getStyle("display").from(target);
          if (displayStyle.substr(0, 6) !== "inline") {
            // Make sure that only block elements receive the given class
            target.className += " " + className;
          }
        });
      }
      doc.execCommand(command, false, nodeName);
      if (eventListener) {
        eventListener.stop();
      }
    }
docs: Execute native query command
  and if necessary modify the inserted node's className