重定义extjs中button被点击后的样式

1.

var btn = new Ext.Button({text:'ddd'});
btn.on('',function(b){
b.addClass('newCSS');
});

2.

/*编辑*/
.edit {
background-image: url(../images/toolbarIcon/edit.png) !important;
}

/*发布*/
.release {
background-image: url(../images/toolbarIcon/release.png) !important;
}

var btn=new Ext.ButtonGroup({

id : 'edit',
text : '编辑',
handler : onRelease,
iconCls : 'edit'//样式图片
});

function onRelease(){
btn.setIconClass('release');//更改图片
btn.setText('发布');
}

{
											id:'_kbkg',
											xtype: 'button',
											text:'打开课表',
											iconCls:'unlock',
											listeners: {
										        'click': function(t){
													var text = t.getText();
													if(text == "打开课表"){
														t.setText("关闭课表");
														t.setIconClass('lock');
														KbCheck(1);
													}if(text == '关闭课表'){
														t.setText("打开课表");
														t.setIconClass('unlock');
														KbCheck(0);
													}
										        	
										        }
										    }
										}

 Ext.getCmp("xn_label").setText(" 学年: " + xn);
 Ext.getCmp("xq_label").setText(" 学期: " + xq);

//课表开关
function KbCheck(v){
Ext.Ajax.request({
 url: contextPath +'/system/lxdmglAction.do?method=getKbkg',
 /*
 success: function(request){
 },
 failure: function(request){
 },
 */
 params: { kva: v}
});
 }
 
Ext.Ajax.request({
<a href="contextPath">url:contextPath</a> +'/system/lxdmglAction.do?method=getKbkgValue',
success:function(request){
rs=Ext.decode(request.responseText);
if (rs=="1") {
Ext.getCmp("_kbkg").setText("关闭课表");
Ext.getCmp("_kbkg").setIconClass('lock');
}
}/*,
failure:function(request){
Ext.Msg.alert("加载课表开关失败，请重试！");
}*/
});