Ext JS 6 treepanel make not expandable

Question

I have following Ext JS tree panel code

  Ext.define('Criteria', {
     extend: 'Ext.tree.Panel'
     alias: 'widget.Criteria',
     cls: 'criteria',
     id: 'criteria',
     style: 'padding: 10px;',
     rootVisible: false,
     expand: false,
     width: 350,
     controller : 'CriteriaVc',
     viewModel : {
        type : 'CriteriaVm'
      },
      listeners: {
        itemexpand  : function(){
           return false;
      }
  }});

My requirement is to make this tree panel not expandable on clicking + icon.I have to show a popup on clicking + icon and in popup I have to show the entire tree.

I achieved showing entire tree in popup using itemclick.But, + icon should not expand the tree.

How can I achieve requiremnt that on clicking + tree should not expandable.