ExtJS自定义组件中的事件传递问题

Ext.define("Ext.ux.comboboxtree", {
  extend: "Ext.form.field.Picker",
  requires: ["Ext.tree.Panel"],
  alias: 'widget.combotree',
  "initComponent": function() {
    var self = this;
    Ext.apply(self, {
      fieldLabel: self.fieldLabel,
      labelWidth: self.labelWidth,
      store: self.store
    });
    self.callParent();
  },
  "createPicker": function() {
    var self = this;
    var store = this.store;
    self.picker = new Ext.tree.Panel({
      height: 150,
      autoScroll: true,
      floating: true,
      focusOnToFront: true,
      shadow: true,
      ownerCt: this.ownerCt,
      useArrows: true,
      store: store,
      rootVisible: false,
      resizable: true
    });
    self.picker.on({
      "itemdblclick": function(combotree, rec){
        if(rec.get('leaf')){
          self.setRawValue(rec.get('id'));
          self.setValue(rec.get('text'));
          self.picker.hide();
          //我想在这里做点什么，以供调用此combotree的“外部”位置使用，但我不知道该怎么做……
        }
      }
    });
    return self.picker;
  },
  "alignPicker": function() {
    var me = this, picker, isAbove, aboveSfx = '-above';
    if (this.isExpanded) {
      picker = me.getPicker();
      if (me.matchFieldWidth) {
        picker.setWidth(me.bodyEl.getWidth());
      }
      if (picker.isFloating()) {
        picker.alignTo(me.inputEl, "", me.pickerOffset);// ""->tl
        isAbove = picker.el.getY() < me.inputEl.getY();
        me.bodyEl[isAbove ? 'addCls' : 'removeCls'](me.openCls
          + aboveSfx);
        picker.el[isAbove ? 'addCls' : 'removeCls'](picker.baseCls
          + aboveSfx);
      }
    }
  }
});

      {
        fieldLabel: '生产厂家',
        name: 'producer',
        id: 'producer',
        xtype: 'combotree',
        store: store
//我想这里选择一个值的时候，也就是上面combotree里的itemdblclick的时候，给下面这个combotree“销售厂家”也赋某一个值
      },{
        fieldLabel: '销售厂家',
        name: 'vendor',
        id: 'vendor',
        xtype: 'combotree',
        store: store
      }

// 假设你是扩展的组件，在initComponent中初始化items的
initComponent : function(){
   ...
   var field1, field2;
   field1 = new XXX();
   field2 = new XXX();
   field1.on("change", function(){
      field2.setValue(field1.getValue());
   });
   this.items = [field1, field2]
   ...
}