下拉框改变值，同时改变另一个TextField的FieldLabel

需要改变FiledLabel的TextField

  this.txt_handle_person = new Ext.form.TextField({
        id:"in_txt_handle_person",
        fieldLabel: "经手人员",
        width: this.controlWidth
    });

下拉框设置监听：

  this.inTypeStore = new Ext.data.SimpleStore({
        fields: ["id", "text"],
        data: [
            [1,"采购入库"],[2,"退货入库"], [3,"盘点入库"]
        ]
    });
    this.combo_type = new Ext.form.ComboBox({
        fieldLabel: "入库类型",
        valueField: 'id',
        displayField: 'text',
        name: 'text',
        store: this.inTypeStore,
        typeAhead: true,
        mode: 'local',
        triggerAction: 'all',
        selectOnFocus: true,
        forceSelection: true,
        editable: false,
        width:this.controlWidth,
        allowBlank: false,
        value:1//默认值
       ,listeners:{
            scope: this,
            'select': this.change.createDelegate(this)
        }
    });

监听方法：

 change:function(){
       if(this.combo_type.getValue()==3){//当下拉框值为3时则修改fieldLabel
          var txt =  Ext.getCmp('in_txt_handle_person').getEl().parent().parent().first();
           txt.dom.innerHTML="盘点人员:";
        }else{
           var txt =  Ext.getCmp('in_txt_handle_person').getEl().parent().parent().first();
           txt.dom.innerHTML=" 经手人员:";
        }