title: ExtJS 4 drag and drop wait for asynchronous action before deciding to complete the drop (or not)
body: <p>Using ExtJS 4.07, I have a simple tree which loads data from the server:</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      Ext.onReady(function () {
          Ext.create('Ext.Viewport', {
              layout: 'border',
              items: [
                  { id: 'centerpanel', region: 'center', layout: 'fit' },
              ]
          });
  
          var store = Ext.create('Ext.data.TreeStore', {
              proxy: {
                  type: 'ajax',
                  url: '/getlist'
              },
              root: {
                  text: 'data',
                  id: '/',
                  expanded: true
              }
          });
  
          var treelist = Ext.create('Ext.tree.Panel', {
              id: 'tree',
              store: store,
              width: 500,
              height: 500,
              viewConfig: {
                  plugins: {
                      ptype: 'treeviewdragdrop',
                  },
              }
          });  
  
          Ext.getCmp('centerpanel').add(treelist);
      });
  &lt;/script&gt;
  </code></pre>
  
  <p>The problem is: how can I wait for a asynchronous action to complete (for example, an extjs popup or an ajax request) after you have dragged an item to another location in the same tree.</p>
  
  <p>Can someone give me a hint or point me to the correct direction?</p>