 + options.firstLineNumber : "\u00a0") + "</div>");
       }
       gutter.style.display = "none"; // TODO test whether this actually helps
       gutter.innerHTML = html.join("");
@@ -1371,10 +1377,8 @@ var CodeMirror = (function() {
         if (option == "parser") setParser(value);
         else if (option === "lineNumbers") setLineNumbers(value);
         else if (option === "gutter") setGutter(value);
-        else if (option === "readOnly") options.readOnly = value;
-        else if (option === "inden