restrict run to langNim

forms.tmpl

@@ -241,7 +241,7 @@
     element.appendChild(runDiv);
   }
   function appendRunBtn(){
-    var els = Array.prototype.slice.call(document.getElementsByClassName("listing"));
+    var els = Array.prototype.slice.call(document.getElementsByClassName("langNim"));
     els.forEach(appendEachRunBtn, this);
   }
   appendRunBtn()

utils.nim

@@ -28,6 +28,7 @@ type
 var docConfig: StringTableRef
 
 docConfig = rstgen.defaultConfig()
+docConfig["doc.listing_start"] = "<pre class=\"listing $2\">"
 docConfig["doc.smiley_format"] = "/images/smilieys/$1.png"
 
 proc loadConfig*(filename = getCurrentDir() / "forum.json"): Config =