extJs 文本框后面加上说明文字+下拉列表选中值后触发事件

var showform;
function panelshowform()
{
showform=null;
showform = new ext.formpanel({
renderto:"showpanel",
region:'north',
border:false,
bodyborder:false,
frame:true,
waitmsgtarget: true,
labelalign:'right',
id:"showform",
items:[{
layout:'column',
labelwidth:129,
items:[
{
columnwidth:.6,
layout:'form',
items:{
name:"enable",
hiddenname:"enable",
fieldlabel:'是否启用密码策略',
xtype:'combo',
editable: false,//不允许输入 lazyrender:true,
blanktext : '必须启用密码的侧咯', //为空默认值
allowblank : false, //不允许为空
mode: 'local',
triggeraction: 'all',
store:new ext.data.simplestore({
fields: ["value", "text"], data: [['1','启用'],['0','禁用']]
}),
// 这两项要与上面的fields对应
valuefield :"value",
displayfield: "text",
listeners:{ change:function(){changevalue();}
},
anchor:'100%'
}
},{
columnwidth:.4,
layout:'form',
items:{
hiddenname:"infofillone",
name:"infofillone",
xtype:'label',
html:'<font color=red>设置为禁用,则以下面项不可用</font>',
labelseparator:'',
anchor:'100%'
}
},{
columnwidth:.6,
layout:'form',
items:{hiddenname:"updateday",
name:"updateday",
xtype:'textfield',
fieldlabel:'更新周期',
emptytext : '设为-1该项被禁用',
maxlength:'100',
readonly:false,
vtype:'day',
anchor:'100%'
}
},{
columnwidth:.4,
layout:'form',
items:{
hiddenname:"info",
name:"info",
xtype:'label',
//labelalign:'left',
html:
'<font color=red>设置为-1,则该项被禁用</font>',
labelseparator:'',
anchor:'100%'
}
}]
}]
})
}

/**
*是否启用密码的触发事件
*/
function changevalue()
{
if(queryform.form.findfield('enable').getvalue()=="0")
{
$("updateday").disabled = true;
}else{
$("updateday").disabled = false;
}
}
/**
*窗口的显示
*/
function input()
{
panelshowform();
win=new ext.window({
title:"extjs 文本框后加上说明文",
width:200, //窗口初始width值
hight:200, //窗口初始hight值
x:100, //窗口初始的x位置
y:100, //窗口初始的y位置
plain : true,
modal : true, //模式窗口
maximizable:true,最大化显示
resizable:false, //窗口的大小不允许拖动
items:[showform]
})
}