title: Sencha Touch store sync callback
body: <p>My store.sync() can return success:false, and if it does, I would like to use something similar to Ext's <code>failure</code> callback to react to the error appropriately, but I did not find a possibility to use any builtin ST functions for this. sync has neither callback nor success nor failure option available in ST.</p>
  
  <p>What did I overlook?</p>
  
  <p>PS: I did find a workaround for <code>success</code> callback at <a href="https://stackoverflow.com/questions/14014068/why-is-there-no-sync-callback-in-sencha-touch/14322956#14322956">Why is there no sync callback in Sencha Touch?</a> but I need <code>failure</code> callback.</p>