ExtJs HtmlEditor ReadOnly 无效

//任务内容信息(编辑器)
        var LogMsgEdit=new Ext.form.HtmlEditor({
            id:"LogMsgEdit",
            name:"LogMsgEdit",
            fieldLabel:"任务内容",
            width:450
        });
        /*LogMsgEdit中readOnly无效，下面方法重写HtmlEditor可以实现HtmlEditor只读属性
        http://www.sencha.com/forum/showthread.php?26657-FIXED-92-3.0.0-2.x-HtmlEditor-readOnly-and-disabled-not-working&highlight=htmleditor+property         */
        Ext.override(Ext.form.HtmlEditor, {
/**
	 * Set a readonly mask over the editor
	 * @param {Boolean} readOnly - True to set the read only property, False to switch to the editor
	 */
	setReadOnly: function(readOnly){
		if(readOnly){
			this.syncValue();
			var roMask = this.wrap.mask();
	          roMask.dom.style.filter = "alpha(opacity=0);"; //IE
               roMask.dom.style.opacity = "0"; //Mozilla
               roMask.dom.style.background = "white";
               roMask.dom.style.overflow = "scroll";

			this.el.dom.readOnly = true;
		} else {
			if(this.rendered){
				this.wrap.unmask();
			}
			this.el.dom.readOnly = false;
		}
	}
});

//页面加载的时候，设置该控件的ReadOnly为只读 
Ext.getCmp("LogMsgEdit").setReadOnly(true);