I think we should move the invocation of the `init` method's callback into this callback, i.e.

```diff
    this.fullHeight = ThreadListUI.view.offsetHeight;
-   // Callback if needed
-   if (callback && typeof callback === 'function') {
-     callback();
-   }
+   //set MMS size limitation
+   this.getMmsSizeLimitation(function(size) {
+     this.mmsSizeLimitation = size;
+     // Callback if needed
+     if (callback && typeof callback === 'function') {
+       callback();
+     }
+   }.bind(this));
  },
```

And while we're at it, the condition `callback && typeof callback === 'function'` can be simplified to `typeof callback === 'function'`.