extjs 判断前端是否有进行过编辑

form表单提交时要判断form是否被修改过，经进API得知：

BasicForm中有事件可监听到。

 setValues : function(values){
        if(Ext.isArray(values)){ // array of objects
            for(var i = 0, len = values.length; i < len; i++){
                var v = values[i];
                var f = this.findField(v.id);
                if(f){
                    f.setValue(v.value);
                    if(this.trackResetOnLoad){
                        f.originalValue = f.getValue();
                    }
                }
            }
        }else{ // object hash
            var field, id;
            for(id in values){
                if(typeof values[id] != 'function' && (field = this.findField(id))){
                    field.setValue(values[id]);
                    if(this.trackResetOnLoad){
                        field.originalValue = field.getValue();
                    }
                }
            }
        }
        return this;
    }