Hack to get something approximating paint rectangles with React/om. Has very rough edges!

utils.clj

(defmacro html [body]
  `(if-not (:render-colors? initial-query-map)
     (html/html ~body)
     (let [body# ~body]
       (try
         (let [[tag# & rest#] body#
               attrs# (if (map? (first rest#))
                        (first rest#)
                        {})
               rest# (if (map? (first rest#))
                       (rest rest#)
                       rest#)]
           (html/html (vec (concat [tag# (assoc-in attrs# [:style :border] (str "5px solid rgb("
                                                                                (rand-int 255)
                                                                                ","
                                                                                (rand-int 255)
                                                                                ","
                                                                                (rand-int 255)
                                                                                ")"))]
                                   rest#))))
         (catch :default e#
           (html/html body#))))))

Example of it in action, showing how much extra rendering to the virtual dom we were doing: http://g.recordit.co/bTVTRWEwtZ.gif