title: List scroll issue
body: <p>I've a problem with my List. I can't scroll them. The list move down but jump to the top after tapend.
  I use Sencha touch PR4 and i have test this on Ipad and Google Chrome</p>
  
  <p>I use this view</p>
  
  <pre><code>Ext.define('TimeShift.view.Activity', {
      extend: 'Ext.Panel',
      id: 'Activity',
      alias: 'widget.Activity',
      layout: 'card',
      config: {
          items: [
              { xtype: 'list',
                  layout: 'card', //    fullscreen: true,
                  store: 'ActivityStore',
                  scrollable: 'vertical',
                  itemTpl: '&lt;div class="contact"&gt;{Purpose}&lt;/div&gt;',
                  items: [
                      {
                          xtype: 'toolbar',
                          docked: 'top',
                          title: 'Aktivit&amp;#228;ten'
                      }] 
      }]
      },
      initialize: function () {
          console.log('initialize ActivityList');
          this.callParent();
      }
  });
  </code></pre>
  
  <p>and this view is in this container</p>
  
  <pre><code>Ext.define('TimeShift.view.ListContainer', {
      extend: 'Ext.Container',
      id: 'ListContainer',
      alias: 'widget.ListContainer',
  
      cardAnimation: 'slider',
      scrollable: true,
      autoDestroy: true,
      config: {
          items: [
  
              { xtype: 'Activity' }
          ]
  
      },
      initialize: function () {
          console.log('initialize ListContainer');
          this.callParent();
      }
  });
  </code></pre>
  
  <p>I hope someone can help me.</p>