extjs动态改变combobox的editable属性

//我能否在工号（usercode）的listeners里设置 用户权限（priority）的editable为true？怎么设置？直接用setDisabled（）等就不能随form.submit（）提交了；用setvisible就看不见了。谢谢了！

var StudentFormPanel = function() {/**$$$$$ */
var Width1=200;
var _form=this;
this.idTextField = {
// xtype : 'hidden',
xtype : 'textfield',
fieldLabel : "序号",
readOnly :true,
width:Width1,
name : "id"
};
this.usercodeTextField = {
xtype : 'textfield',
fieldLabel : "工号",
allowBlank : false,
maxLength:10,
minLength:1,
width:Width1,
regex: /^[0-9]{4,4}$/,
regexText:'只能输入四位数字!',
name : "usercode"
  ,listeners : {
'blur' : function (t, e) {
//我能否在此处设置 用户权限（priority）的editable为true？怎么设置？直接用setDisabled（）等就不能随form.submit（）提交了；用setvisible就看不见了。谢谢了！ 
//var form = Ext.getCmp('regform');
var code = _form.getForm().findField("usercode").getValue();
if (code != '') {   
  Ext.Ajax.request({   
  url : 'yh.myaction?method=chkUsercode',
  //method : 'post',   
  params : {   
  usercode : code   
  },   
  success : function(response, options) {   
  var responseArray = Ext.util.JSON.decode(response.responseText);
  if (responseArray.message) {   
  //isUserCodeOK = false;   
  _form.form.findField("usercode")   
  .markInvalid('工号已被使用！');   
  } else {   
  //isUserCodeOK = true;   
  _form.form.findField("usercode").clearInvalid();   
  }   
  },
  failure:function(response, options){
  Ext.Msg.alert('提示', '后台错误!');
  }   
  })  
  }   
}
}
};
this.passwordTextField = {
xtype : 'textfield',
fieldLabel : "密码",
allowBlank : false,
maxLength:10,
minLength:1,
//inputType: 'password',
width:Width1,
regex:/^.{4,8}$/,
regexText:'长度4-8位',
name : "password"
};
this.usernameTextField = {
xtype : 'textfield',
fieldLabel : "姓名",
allowBlank : false,
maxLength:10,
minLength:1,
width:Width1,
name : "username"
};
this.sbpartidtTextField = {
  xtype: 'combo',
  fieldLabel: '部门',
  name: 'sbpartidt',
store:dsBm,
  mode: 'local',
triggerAction: 'all',
  valueField: 'value',
  displayField: 'text',
  width:Width1,
  editable:false,  
  hiddenName:'sbpartid'
  };
this.tjflagtTextField = {
  xtype: 'combo',
  fieldLabel: '统计标志',
  name: 'tjflagt',
  store: new Ext.data.SimpleStore({
  fields: ['value', 'text'],
  data : [
  ['0', '否'],
  ['1', '是']
  ]
  }),
  mode: 'local',
triggerAction: 'all',
  valueField: 'value',
  displayField: 'text',
  editable :false,
  width:Width1,
  hiddenName:'tjflag'
  };
this.priorityTextField = {
xtype: 'lovcombo',
fieldLabel: '用户权限',
name: 'priorityt',
store:new Ext.data.SimpleStore({
  fields: ['value', 'text'],
  data : [
  ['t', '填报'],
  ['c', '查询'],
  ['s', '审核'],
  ['g', '管理'],
['j', '统计']
  ]
  }),//填报t，查询c，审核s，管理g，统计j
mode: 'local',
triggerAction: 'all',
valueField: 'value',
displayField: 'text',
editable :false,
width:Width1,
hiddenName:'priority'
};


StudentFormPanel.superclass.constructor.call(this, {
bodyStyle : 'padding:5px 5px 0',
frame : true,
labelWidth:55,
reader : new Ext.data.JsonReader( {
root : 'list',
successProperty : 'success',
totalProperty : 'totalSize',
id : 'id'
}, ['id','usercode','password','username','sbpartid','tjflag','priority']),/**$$$$$ */
items : [this.idTextField, this.usercodeTextField, this.passwordTextField, this.usernameTextField, this.sbpartidtTextField, this.tjflagtTextField, this.priorityTextField]
});
}
Ext.extend(StudentFormPanel, Ext.form.FormPanel, {
loadData : function(id) {
var url = thisServlet + '?method=edit&id=' + id;/**$$$$$ */
this.getForm().load( {
url : url,
waitMsg : 'Loading',
failure : function(form, action) {
var json = action.response.responseText;
var o = eval("(" + json + ")");
Ext.MessageBox.show( {
title : 'Error',
msg : o.message,
buttons : Ext.MessageBox.OK,
icon : Ext.MessageBox.ERROR
});
}
});
}
});


// 配置 readOnly:true

blur : function(obj){
    obj.getEl().dom.readOnly = true;

}