title: ExtJS 4.2.1 resetting Stores on ViewChange
body: <p>in my ExtJS application I want to reset the stores when I change the page. 
  Which means I don't want any filters, groupings or listener from any old view/page.</p>
  
  <p>Currentyl I am setting the store of my view like this:</p>
  
  <pre><code>{
     xtype: 'admingrid',
     ...
     columns: [
        ...
     ],
     store: 'appname.store.administration.User'
  }
  </code></pre>
  
  <p>I am loading the store like that:</p>
  
  <pre><code>onAfterRender: function() {
      //load all users
      this.setUserStore(this.getUserGrid().getStore());
      this.getUserStore().load();
  },
  </code></pre>
  
  <p>and in some cases like this:</p>
  
  <pre><code>onAfterRender: function() {
      //load all users
      this.setUserStore(Ext.StoreManager.lookup('appname.store.administration.User'));
      this.getUserStore().load();
  },
  </code></pre>
  
  <p>all my my pages extends my Base view and so I thought I just do something like this:</p>
  
  <pre><code>Ext.define("appname.view.Base", {
      extend: 'Ext.panel.Panel',
      ui: 'basepanel',
  
      padding: 15,
      contentPaddingProperty: 'padding',
  
      listeners: {
          beforedestroy: function() {
              Ext.StoreManager.each(function (item, index, len) {
                   item.clearFilter(true); // param: suppressEvent
                   item.clearGrouping();
                   item.clearListeners(); // this will also remove managed listeners                                  
              });
          }
      }   
  });
  </code></pre>
  
  <p>this will cause that the grid is sometimes empty when I am entering the view the first time... I don't understand why.. when I am entering the view the second or sometimes the third time it does show the grid with the entries.. </p>
  
  <p>Is there a common way to accomplish such a thing? What I am doing wrong? I don't understand why this is happening. </p>