title: Cancel node drop
body: <p>I want to validate a node before dropping it on tree.
  I used beforenodedrop event for this purpose but validation is occured on server side so as response does not come in time and function always return true so node is dropped. i want to know which method/event should be used for this purpose</p>
  
  <p>Here is my code for beforenodedrop event</p>
  
  <pre><code>treeList_fnBeforeNodeDrop = function (e){     
      if(e.target.attributes.LocationLevel&lt;=e.data.node.attributes.LocationLevel)//if node is dropped on node of previous level
      {
         return true;
      }else{ //If node is dropped on level greather than its level like region into area verify its hierarchy
  
          Ext.Ajax.request({
              method: 'POST',
              url: this.webService + '/ValidateNodeDrop',
              params: {DropLocationId: e.data.node.id,ParentLocationId:e.target.id, TargetLocationLevel:e.target.attributes.LocationLevel},
              success: function ( result, request ) {
                   return true;
              },
              failure: function ( result, request ) {
                  Ext.Msg.alert('Failure', 'You can not drop node at this level');
  
                  return false;
              }
          });
  
      }
  }
  </code></pre>
  
  <p>Please help me what mistake i have done</p>