messageHandler expects object instead of string

qt.js

@@ -1,12 +1,22 @@
 (function() {
-    var QtProvider = function() {};
+    var QtProvider = function() {
+        this.handlers = [];
+        
+        var self = this;
+        navigator.qt.onmessage = function (message) {
+            self.handlers.forEach(function (handler) {
+                handler.call(self, JSON.parse(message));
+            });
+        }
+    };
+
     QtProvider.prototype.send = function(payload) {
         navigator.qt.postData(JSON.stringify(payload));
     };
 
     Object.defineProperty(QtProvider.prototype, "onmessage", {
         set: function(handler) {
-            navigator.qt.onmessage = handler;
+            this.handlers.push(handler);
         },
     });